% BibTeX Exporter written in LotusScript by Uwe Brahm, % Please send bug reports via email to . Thanks. % Exported: Thursday, 28. March 2024, 12:13, Server: halma/MPII/DE @MASTERSTHESIS{Abdu95, AUTHOR = {Ayari, Abdelwaheb}, TITLE = {A Reinterpretation of the Deductive Tableaux System in Higher-Order Logic}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {June}, YEAR = {1995}, ABSTRACT = {Our research investigates frameworks supporting the formalization of programming calculi and their application to deduction-based progr am synthesis. Here we report on a case study: within a conservative extension of higher-order logic implemented in the Isabelle system, we derived rules for program development which can simulate those of the deductive tableau proposed by Manna and Waldinger. We have used the resulting theory to synthesize a library of verified programs, focusing in particular on sorting algorithms. Our experience suggests that the methodology we propose is well suited both to implement and use programming calculi, extend them, partially automate them, and even formally reason about their correctness.}, } @INPROCEEDINGS{AbduBasin-TACAS96, AUTHOR = {Ayari, Abdelwaheb and Basin, David A.}, EDITOR = {Margaria, Tiziana and Steffen, Bernhard}, TITLE = {Generic System Support for Deductive Program Development}, BOOKTITLE = {Second International Workshop, TACAS'96: Tools and Algorithms for the Construction and Analysis of Systems}, PADDRESS = {Berlin, Germany}, ADDRESS = {Passau, Germany}, PUBLISHER = {Springer}, MONTH = {March}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1055}, ISBN = {3-540-61042-1}, YEAR = {1996}, PAGES = {313--328}, ABSTRACT = {We report on a case study in using logical frameworks to support the formalization of programming calculi and their application to deduction-based program synthesis. Within a conservative extension of higher-order logic implemented in the Isabelle system, we derived rules for program development that can simulate those of the deductive tableau proposed by Manna and Waldinger. We have used the resulting theory to synthesize a library of verified programs, focusing on sorting algorithms. Our experience suggests that the methodology we propose is well suited both to implement and use programming calculi, extend them, partially automate them, and even formally reason about their correctness.}, } @INPROCEEDINGS{AfshordelHillenbrandWeidenbach01, AUTHOR = {Afshordel, Bijan and Hillenbrand, Thomas and Weidenbach, Christoph}, EDITOR = {Nieuwenhuis, Robert and Voronkov, Andrei}, TITLE = {First-Order Atom Definitions Extended}, BOOKTITLE = {Proceedings of the 8th International Conference on Logic for Programming, Artificial Intelligence, and Reasoning (LPAR-2001)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Havanna, Cuba}, PUBLISHER = {Springer}, MONTH = {December}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2250}, YEAR = {2001}, PAGES = {309--319}, } @MASTERSTHESIS{Althaus-Diplom98, AUTHOR = {Althaus, Ernst}, TITLE = {{Berechnung optimaler Steinerb{\"a}ume in der Ebene}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {December}, YEAR = {1998}, } @INPROCEEDINGS{AmadioCharatonik2002, AUTHOR = {Charatonik, Witold and Amadio, Roberto}, EDITOR = {Brim, Lubos and Jancar, Petr and Kretinsky, Mojomir and Kucera, Antonin}, TITLE = {On Name Generation and Set-Based Analysis in the Dolev-Yao Model}, BOOKTITLE = {CONCUR 2002 - Concurrency Theory. 13th International Conference}, PADDRESS = {Berlin, Germany}, ADDRESS = {Brno, Czech Republic}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2421}, ISBN = {3-540-44043-7}, YEAR = {2002}, PAGES = {499--514}, ABSTRACT = {We study the control reachability problem in the Dolev-Yao model of cryptographic protocols when principals are represented by tail recursive processes with generated names. We propose a conservative approximation of the problem by reduction to a non-standard collapsed operational semantics and we introduce checkable syntactic conditions entailing the equivalence of the standard and the collapsed semantics. Then we introduce a conservative and decidable set-based analysis of the collapsed operational semantics and we characterize a situation where the analysis is exact.}, } @INPROCEEDINGS{Anderson&Basin, AUTHOR = {Anderson, Penny and Basin, David A.}, TITLE = {Deriving and Applying Logic Program Transformers}, BOOKTITLE = {Algorithms, Concurrency and Knowledge (1995 Asian Computing Science Conference)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Pathumthani, Thailand}, PUBLISHER = {Springer}, MONTH = {December}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1023}, YEAR = {1995}, PAGES = {301--318}, } @INPROCEEDINGS{AntoyEchahedHanus94a, AUTHOR = {Antoy, Sergio and Echahed, Rachid and Hanus, Michael}, TITLE = {A Needed Narrowing Strategy}, BOOKTITLE = {Proceedings of the 21st ACM Symposium on Principles of Programming Languages (POPL'94)}, PADDRESS = {New York, USA}, ADDRESS = {Portland, USA}, PUBLISHER = {ACM}, YEAR = {1994}, PAGES = {268--279}, NOTE = {Extended version available as Research Report MPI-I-93-243, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken, Germany}, ABSTRACT = {Narrowing is the operational principle of languages that integrate functional and logic programming. We propose a notion of a needed narrowing step that, for inductively sequential rewrite systems, extends the Huet and Levy notion of a needed reduction step. We define a strategy, based on this notion, that computes only needed narrowing steps. Our strategy is sound and complete for a large class of rewrite systems, is optimal w.r.t. the cost measure that counts the number of distinct steps of a derivation, computes only independent unifiers, and is efficiently implemented by pattern matching.}, } @ARTICLE{ArecesRijkeNivelle02, AUTHOR = {Areces, Carlos and de Rijke, Maarten and de Nivelle, Hans}, JOURNAL = {Journal of Logic and Computation}, TITLE = {Resolution in modal, description and hybrid logic}, ADDRESS = {Oxford, UK}, NUMBER = {5}, PUBLISHER = {Oxford University Press}, MONTH = {October}, VOLUME = {11}, ISBN = {0955-792X}, YEAR = {2001}, PAGES = {717--736}, } @INPROCEEDINGS{ArgonEtAlSofSem2001, AUTHOR = {Argon, Pablo and Delzanno, Giorgio and Mukhopadhyay, Supratik and Podelski, Andreas}, EDITOR = {Pacholski, Leszek and Ruzicka, Peter}, TITLE = {Model Checking for Communication Protocols}, BOOKTITLE = {Proceedings of the 28th Annual Conference on Current Trends in Theory and Practice of Informatics (SOFSEM-2001)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Piestany, Slovak Republic}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2234}, ISBN = {3-540-42912-3}, YEAR = {2001}, PAGES = {160--170}, NOTE = {To appear.}, } @MASTERSTHESIS{AutexierDipl96, AUTHOR = {Autexier, Serge}, TITLE = {{Heuristiken zum Beweisen von Gleichungen}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1996}, } @ARTICLE{AvenhausHillenbrandLoechner2003, AUTHOR = {Avenhaus, J{\"u}rgen and Hillenbrand, Thomas and L{\"o}chner, Bernd}, JOURNAL = {Journal of Symbolic Computation}, TITLE = {On Using Ground Joinable Equations in Equational Theorem Proving}, ADDRESS = {Amsterdam, The Netherlands}, NUMBER = {1-2}, PUBLISHER = {Elsevier}, VOLUME = {36}, ISBN = {0747-7171}, YEAR = {2003}, PAGES = {217--233}, ABSTRACT = {When rewriting and completion techniques are used for equational theorem proving, the axiom set is saturated with the aim to get a rewrite system that is terminating and confluent on ground terms. To reduce the computational effort it should (1) be powerful for rewriting and (2) create not too many critical pairs. These problems become especially important if some operators are associative and commutative (\AC). We show in this paper how these two goals can be reached to some extent by using ground joinable equations for simplification purposes and omitting them from the generation of new facts. % For the special case of \AC-operators we present a simple redundancy criterion which is easy to implement, efficient, and effective in practice, leading to significant speed-ups.}, } @ARTICLE{AyariBasin2001, AUTHOR = {Ayari, Abdelwaheb and Basin, David A.}, JOURNAL = {Journal of Symbolic Computation}, TITLE = {A Higher-order Interpretation of Deductive Tableau}, NUMBER = {5}, MONTH = {May}, VOLUME = {31}, YEAR = {2001}, PAGES = {487--520}, ABSTRACT = {The Deductive Tableau of Manna and Waldinger is a formal system with an associated methodology for synthesizing functional programs by existence proofs in classical first-order theories. We reinterpret the formal system in a setting that is higher-order in two respects: higher-order logic is used to formalize a theory of functional programs and higher-order resolution is used to synthesize programs during proof. Their synthesis methodology can be applied in our setting as well as new methodologies that take advantage of these higher-order features. The reinterpretation gives us a framework for directly formalizing and implementing the Deductive Tableau system in standard theorem provers that support the kinds of higher-order reasoning listed above. We demonstrate this, as well as a new development methodology, within a conservative extension of higher-order logic in the Isabelle system. We report too on a case-study in synthesizing sorting programs.}, } @ARTICLE{BaaderOhlbach95, AUTHOR = {Baader, Franz and Ohlbach, Hans J{\"u}rgen}, JOURNAL = {Journal of Applied Non-Classical Logics}, TITLE = {A Multi-Dimensional Terminological Knowledge Representation Language}, NUMBER = {2}, VOLUME = {5}, YEAR = {1995}, PAGES = {153--198}, ABSTRACT = {An extension of the concept description language \alc\ used in {\sc kl-one}-like terminological reasoning is presented. The extension includes multi--modal operators that can either stand for the usual role quantifications or for modalities such as belief, time etc. The modal operators can be used at all levels of the concept terms, and they can be used to modify both concepts and roles. This is an instance of a new kind of combination of modal logics where the modal operators of one logic may operate directly on the operators of the other logic. Different versions of this logic are investigated and various results about decidability and undecidability are presented. The main problem, however, decidability of the basic version of the logic, remains open}, } @MASTERSTHESIS{Bach96, AUTHOR = {Bach, Alexander}, TITLE = {Static analysis of functional programs via Linear Logic}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1996}, ABSTRACT = {This thesis investigates aspects of the general relationship between simply typed lambda-calculus and a linear term calculus based on Intuitionistic Linear Logic. It introduces a notion of minimization on linear lambda-terms that removes super ous nonlinear operations (storage). Two different embeddings of the simply typed lambda-calculus into the linear term calculus are studied with respect to their properties under minimization. We define operational semantics for both term calculi. In support of Abramsky's thesis, that linear types are useful in doing abstract interpretation of functional programs, we demonstrate - using translation together with minimization - a syntactic method to do strictness analysis on lambda-terms, via the linear typing calculus. This leads to useful optimizations of call-by-name reduction on lambda-terms.}, } @INPROCEEDINGS{Bachmair-et-al-92-cade, AUTHOR = {Bachmair, Leo and Ganzinger, Harald and Lynch, Christopher and Snyder, Wayne}, EDITOR = {Kapur, D.}, TITLE = {Basic Paramodulation and Superposition}, BOOKTITLE = {Proceedings of the 11th International Conference on Automated Deduction (CADE-11)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Saratoga Springs, NY}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {607}, YEAR = {1992}, PAGES = {462--476}, ABSTRACT = {We introduce a class of restrictions for the ordered paramodulation and superposition calculi (inspired by the {\it basic\/} strategy for narrowing), in which paramodulation inferences are forbidden at terms introduced by substitutions from previous inference steps. These refinements are compatible with standard ordering restrictions and are complete without paramodulation into variables or using functional reflexivity axioms. We prove refutational completeness in the context of deletion rules, such as simplification by rewriting (demodulation) and subsumption, and of techniques for eliminating redundant inferences. Finally, we discuss experimental data obtained both from a modification of Otter and from our prototype Lisp implementation.}, } @ARTICLE{Bachmair-et-al-95-ic, AUTHOR = {Bachmair, Leo and Ganzinger, Harald and Lynch, Christopher and Snyder, Wayne}, JOURNAL = {Information and Computation}, TITLE = {Basic Paramodulation}, NUMBER = {2}, PUBLISHER = {Academic Press}, VOLUME = {121}, ISBN = {0890-5401}, YEAR = {1995}, PAGES = {172--192}, NOTE = {Revised version of TR MPI-I-93-236, 1993}, ABSTRACT = {We introduce a class of restrictions for the ordered paramodulation and superposition calculi (inspired by the {\em basic\/} strategy for narrowing), in which paramodulation inferences are forbidden at terms introduced by substitutions from previous inference steps. In addition we introduce restrictions based on term selection rules and redex orderings, which are general criteria for delimiting the terms which are available for inferences. These refinements are compatible with standard ordering restrictions and are complete without paramodulation into variables or using functional reflexivity axioms. We prove refutational completeness in the context of deletion rules, such as simplification by rewriting (demodulation) and subsumption, and of techniques for eliminating redundant inferences.}, } @INCOLLECTION{BachmairGanzinger-01-har, AUTHOR = {Bachmair, Leo and Ganzinger, Harald}, EDITOR = {Robinson, J. A. and Voronkov, A.}, TITLE = {Resolution Theorem Proving}, BOOKTITLE = {Handbook of Automated Reasoning}, CHAPTER = {2}, ADDRESS = {Amsterdam, the Netherlands}, PUBLISHER = {Elsevier}, VOLUME = {1}, YEAR = {2001}, PAGES = {19--99}, ABSTRACT = {We review the fundamental resolution-based methods for first-order theorem proving and present them in a uniform framework. We show that these calculi can be viewed as specializations of non-clausal resolution with simplification. Simplification techniques are justified with the help of a rather general notion of redundancy for inferences. As simplification and other techniques for the elimination of redundancy are indispensable for an acceptable behaviour of any practical theorem prover this work is the first uniform treatment of resolution-like techniques in which the avoidance of redundant computations attains the attention it deserves. In many cases our presentation of a resolution method will indicate new ways of how to improve the method over what was known previously. We also give answers to several open problems in the area.}, } @INPROCEEDINGS{BachmairGanzinger-91-ctrs, AUTHOR = {Bachmair, Leo and Ganzinger, Harald}, EDITOR = {Kaplan, St. and Okada, M.}, TITLE = {Completion of first-order clauses with equality by strict superposition}, BOOKTITLE = {Proceedings of the 2nd International Workshop on Conditional and Typed Rewriting}, PADDRESS = {Berlin, Germany}, ADDRESS = {Montreal, Canada}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {516}, YEAR = {1991}, PAGES = {162--180}, ABSTRACT = {We have previously shown that strict superposition together with merging paramodulation is refutationally complete for first-order clauses with equality. This paper improves these results by considering a more powerful framework for simplification and elimination of clauses. The framework gives general criteria under which simplification and elimination do not destroy the refutation completeness of the superposition calculus. One application is a proof of the refutation completeness for alternative superposition strategies with arbitrary selection functions for negative literals. With these powerful simplification mechanisms it is often possible to compute the closure of nontrivial sets of clauses under superposition in a finite number of steps. Refutation or solving of {\em goals\/} for such closed or {\em complete\/} sets of clauses is simpler than for arbitrary sets of clauses. The results in this paper contain as special cases or generalize many known results about about ordered Knuth-Bendix-like completion of equations, of Horn clauses, of Horn clauses over built-in Booleans, about completion of first-order clauses by clausal rewriting, and inductive theorem proving for Horn clauses.}, } @INPROCEEDINGS{BachmairGanzinger-91-iclp, AUTHOR = {Bachmair, Leo and Ganzinger, Harald}, TITLE = {Perfect model semantics for logic programs with equality}, BOOKTITLE = {Proceedings International Conference on Logic Programming '91}, PADDRESS = {Cambridge, USA}, ADDRESS = {Paris, France}, PUBLISHER = {MIT Press}, YEAR = {1991}, PAGES = {645--659}, ABSTRACT = {We develop a perfect model semantics for logic programs with negation and equality. Our approach is based on ordered rewriting, a fundamental technique used in equational programming. A logic program in our sense is a set of first-order clauses with equality together with a well-founded ordering on terms and atoms. We show that any consistent logic program has a unique perfect model, provided the ordering is total on ground expressions. The key to this result is a notion of saturation of a set of formulas (under certain inference rules) together with a related concept of redundancy. Our techniques can be applied to Prolog-programs (without equality), in which case a class of programs can be characterized via the notion of stratification up to redundancy for which unique perfect models exist. This extends previous results on (local and weak) stratification.}, } @INPROCEEDINGS{BachmairGanzinger-92-lpar, AUTHOR = {Bachmair, Leo and Ganzinger, Harald}, EDITOR = {Voronkov, A.}, TITLE = {Non-Clausal Resolution and Superposition with Selection and Redundancy Criteria}, BOOKTITLE = {Logic Programming and Automated Reasoning}, PADDRESS = {Berlin, Germany}, ADDRESS = {St.\ Petersburg, Russia}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {624}, YEAR = {1992}, PAGES = {273--284}, ABSTRACT = {We extend previous results about resolution and superposition with ordering constraints and selection functions to the case of general (quantifier-free) first-order formulas with equality. The refutation completeness of our calculi is compatible with a general and powerful redundancy criterion which includes most (if not all) techniques for simplifying and deleting formulas. The spectrum of first-order theorem proving techniques covered by our results includes ordered resolution, positive resolution, hyper-resolution, semantic resolution, set-of-support resolution, and Knuth/Bendix completion, as well as their extension to general first-order formulas. An additional feature in the latter case is our efficient handling of equivalences as equalities on the level of formulas. Furthermore, our approach applies to constraint theorem proving, including constrained resolution and theory resolution.}, } @INPROCEEDINGS{BachmairGanzinger-94-cade, AUTHOR = {Bachmair, Leo and Ganzinger, Harald}, EDITOR = {Bundy, Alan}, TITLE = {Ordered Chaining for Total Orderings}, BOOKTITLE = {Proceedings of the 12th International Conference on Automated Deduction (CADE-12)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Nancy, France}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {814}, YEAR = {1994}, PAGES = {435--450}, NOTE = {Full version available as Research Report MPI-I-93-250, 1993}, ABSTRACT = {We propose inference systems based on ordered chaining and a concept of (global) redundancy for clauses and inferences for dealing with total orderings. A key to the practicality of chaining techniques is the extent to which so-called variable chainings can be restricted. We demonstrate that ordering restrictions and the rewrite techniques which account for their completeness considerably restrict variable chaining. For dense total orderings we show that the techniques for eliminating unshielded variables are admissible simplifications so that no variable chaining is needed at all. We also include equality by combining ordered chaining with superposition.}, } @INPROCEEDINGS{BachmairGanzinger-94-ccl, AUTHOR = {Bachmair, Leo and Ganzinger, Harald}, EDITOR = {Jouannaud, Jean-Pierre}, TITLE = {Buchberger's algorithm: a constraint-based completion procedure}, BOOKTITLE = {Proceedings of the 1st International Conference on Constraints in Computational Logics (CCL'94)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Munich, Germany}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {845}, YEAR = {1994}, PAGES = {285--301}, ABSTRACT = {We present an extended completion procedure with built-in theories defined by a collection of associativity and commutativity axioms and additional ground equations, and reformulate Buchberger's algorithm for constructing Gr\"obner bases for polynomial ideals in this formalism. The presentation of completion is at an abstract level, by transition rules, with a suitable notion of fairness used to characterize a wide class of correct completion procedures, among them Buchberger's original algorithm for polynomial rings over a field.}, } @ARTICLE{BachmairGanzinger-94-jlc, AUTHOR = {Bachmair, Leo and Ganzinger, Harald}, JOURNAL = {Journal of Logic and Computation}, TITLE = {Rewrite-based equational theorem proving with selection and simplification}, INSTITUTION = {Max-Planck-Institut f{\"u}r Informatik}, NUMBER = {3}, PUBLISHER = {Oxford University Press}, VOLUME = {4}, ISBN = {0955-792X}, YEAR = {1994}, PAGES = {217--247}, NOTE = {Revised version of Technical Report MPI-I-91-208, 1991}, ABSTRACT = {We present various refutationally complete calculi for first-order clauses with equality that allow for arbitrary selection of negative atoms in clauses. Refutation completeness is established via the use of well-founded orderings on clauses for defining a Herbrand model for a consistent set of clauses. We also formulate an abstract notion of redundancy and show that the deletion of redundant clauses during the theorem proving process preserves refutation completeness. It is often possible to compute the closure of nontrivial sets of clauses under application of non-redundant inferences. The refutation of goals for such complete sets of clauses is simpler than for arbitrary sets of clauses, in particular one can restrict attention to proofs that have support from the goals without compromising refutation completeness. Additional syntactic properties allow to restrict the search space even further, as we demonstrate for so-called quasi-Horn clauses. The results in this paper contain as special cases or generalize many known results about Knuth-Bendix-like completion procedures (for equations, Horn clauses, and Horn clauses over built-in Booleans), completion of first-order clauses by clausal rewriting, and inductive theorem proving for Horn clauses.}, } @INPROCEEDINGS{BachmairGanzinger-94-lics, AUTHOR = {Bachmair, Leo and Ganzinger, Harald}, TITLE = {Rewrite Techniques for Transitive Relations}, BOOKTITLE = {Proceedings of the 9th IEEE Symposium on Logic in Computer Science}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Paris, France}, PUBLISHER = {IEEE}, YEAR = {1994}, PAGES = {384--393}, NOTE = {Full version available as Technical Report MPI-I-93-249}, ABSTRACT = {We propose inference systems for dealing with transitive relations in the context of resolution-type theorem proving. These inference mechanisms are based on standard techniques from term rewriting and represent a refinement of chaining methods. We establish their refutational completeness and also prove their compatibility with the usual simplification techniques used in rewrite-based theorem provers. A key to the practicality of chaining techniques is the extent to which so-called variable chainings can be restricted. We demonstrate that rewrite techniques considerably restrict variable chaining, though we also show that they cannot be completely avoided for transitive relations in general. If the given relation satisfies additional properties, such as symmetry, further restrictions are possible. In particular, we discuss (partial) equivalence relations and congruence relations.}, } @INPROCEEDINGS{BachmairGanzinger-95-ctrs, AUTHOR = {Bachmair, Leo and Ganzinger, Harald}, EDITOR = {Dershowitz, N. and Lindenstrauss, N.}, TITLE = {Associative-Commutative Superposition}, BOOKTITLE = {Proceedings of the 4th International Workshop on Conditional and Typed Rewrite Systems (CTRS-94)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Jerusalem, Israel}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {968}, YEAR = {1995}, PAGES = {1--14}, NOTE = {Revised version of MPI-I-93-267, 1993}, ABSTRACT = {We present an associative-commutative paramodulation calculus that generalizes the associative-commutative completion procedure to first-order clauses. The calculus is parametrized by a selection function (on negative literals) and a well-founded ordering on terms. It is compatible with an abstract notion of redundancy that covers such simplification techniques as tautology deletion, subsumption, and simplification by (associative-commutative) rewriting. The proof of refutational completeness of the calculus is comparatively simple, and the techniques employed may be of independent interest.}, } @INPROCEEDINGS{BachmairGanzinger-98-cade, AUTHOR = {Bachmair, Leo and Ganzinger, Harald}, EDITOR = {Kirchner, Claude and Kirchner, H{\'e}l{\`e}ne}, TITLE = {Strict Basic Superposition}, BOOKTITLE = {Proceedings of the 15th International Conference on Automated Deduction (CADE-98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Lindau, Germany}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1421}, ISBN = {3-540-64675-2}, YEAR = {1998}, PAGES = {160--174}, ABSTRACT = {In this paper we solve a long-standing open problem by showing that strict superposition---that is, superposition without equality factoring---is refutationally complete. The difficulty of the problem arises from the fact that the strict calculus, in contrast to the standard calculus with equality factoring, is not compatible with arbitrary removal of tautologies, so that the usual techniques for proving the (refutational) completeness of paramodulation calculi are not directly applicable. We deal with the problem by introducing a suitable notion of {\em direct rewrite proof\/} and modifying proof techniques based on candidate models and counterexamples in that we define these concepts, not in terms of semantic truth, but in terms of direct provability. We introduce a corresponding concept of redundancy with which strict superposition is compatible and that covers most simplification techniques.}, } @ARTICLE{BachmairGanzinger-98-jacm, AUTHOR = {Bachmair, Leo and Ganzinger, Harald}, JOURNAL = {Journal of the ACM}, TITLE = {Ordered Chaining Calculi for First-Order Theories of Transitive Relations}, NUMBER = {6}, MONTH = {November}, VOLUME = {45}, ISBN = {0004-5411}, YEAR = {1998}, PAGES = {1007--1049}, NOTE = {Revised Version of MPI-I-95-2-009.}, ABSTRACT = {In this paper we prove decidability results of restricted fragments of simultaneous rigid reachability or SRR, that is the nonsymmetrical form of simultaneous rigid E-unification or SREU. The absence of symmetry enforces us to use different methods, than the ones that have been successful in the context of SREU (for example word equations). The methods that we use instead, involve finite (tree) automata techniques, and the decidability proofs provide precise computational complexity bounds. The main results are 1) monadic SRR with ground rule is PSPACE-complete, and 2) balanced SRR with ground rules is EXPTIME-complete. These upper bounds have been open already for corresponding fragments of SREU, for which only the hardness results have been known. The first result indicates the difference in computational power between fragments of SREU with ground rules and nonground rules, respectively, due to a straightforward encoding of word equations in monadic SREU (with nonground rules). The second result establishes the decidability and precise complexity of the largest known subfragment of nonmonadic SREU.}, } @INCOLLECTION{BachmairGanzinger-98-sppd, AUTHOR = {Bachmair, Leo and Ganzinger, Harald}, EDITOR = {Bibel, Wolfgang and Schmitt, Peter H.}, TITLE = {Equational Reasoning in Saturation-Based Theorem Proving}, BOOKTITLE = {Automated Deduction: A Basis for Applications}, CHAPTER = {11}, ADDRESS = {Dordrecht, The Netherlands}, PUBLISHER = {Kluwer}, VOLUME = {I}, ISBN = {0-7923-5129-0}, YEAR = {1998}, PAGES = {353--397}, ABSTRACT = {In this chapter we describe the theoretical concepts and results that form the basis of state-of-the-art automated theorem provers for first-order clause logic with equality. We mainly concentrate on refinements of paramodulation, such as the superposition calculus, that have yielded the most promising results to date in automated equational reasoning.}, } @INPROCEEDINGS{BachmairGanzingerStuber-95-compass, AUTHOR = {Bachmair, Leo and Ganzinger, Harald and Stuber, J{\"u}rgen}, EDITOR = {Astesiano, Egidio and Reggio, Gianna and Tarlecki, Andrzej}, TITLE = {Combining Algebra and Universal Algebra in First-Order Theorem Proving: The Case of Commutative Rings}, BOOKTITLE = {Recent Trends in Data Type Specification. 10th Workshop on Specification of Abstract Data Types Joint with the 5th COMPASS Workshop}, PADDRESS = {Berlin, Germany}, ADDRESS = {S. Margherita, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {906}, ISBN = {3-540-59132-X}, YEAR = {1995}, PAGES = {1--29}, ABSTRACT = {We present a general approach for integrating certain mathematical structures in first-order equational theorem provers. More specifically, we consider theorem proving problems specified by sets of first-order clauses that contain the axioms of a commutative ring with a unit element. Associative-commutative superposition forms the deductive core of our method, while a convergent rewrite system for commutative rings provides a starting point for more specialized inferences tailored to the given class of formulas. We adopt ideas from the Gr{\"o}bner basis method to show that many inferences of the superposition calculus are redundant. This result is obtained by the judicious application of the simplification techniques afforded by convergent rewriting and by a process called symmetrization that embeds inferences between single clauses and ring axioms.}, } @INPROCEEDINGS{BachmairGanzingerVoronkov-98-cade, AUTHOR = {Bachmair, Leo and Ganzinger, Harald and Voronkov, Andrei}, EDITOR = {Kirchner, Claude and Kirchner, H{\'e}l{\`e}ne}, TITLE = {Elimination of Equality via Transformation with Ordering Constraints}, BOOKTITLE = {Proceedings of the 15th International Conference on Automated Deduction (CADE-98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Lindau, Germany}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1421}, ISBN = {3-540-64675-2}, YEAR = {1998}, PAGES = {175--190}, NOTE = {Short version of MPI-I-97-2-012}, ABSTRACT = {We refine Brand's method for eliminating equality axioms by (i) imposing ordering constraints on auxiliary variables introduced during the transformation process and (ii) avoiding certain transformations of positive equations with a variable on the right-hand side. The refinements are both of theoretical and practical interest. For instance, the second refinement is implemented in Setheo and appears to be critical for that prover's performance on equational problems. The correctness of this variant of Brand's method was an open problem that is solved by the more general results in the present paper. The experimental results we obtained from a prototype implementation of our proposed method for the model elimination prover Protein also show some dramatic improvements of the proof search. Ordering constraints have already been widely used in equational theorem provers based on paramodulation. We prove the correctness of our refinements of Brand's method by establishing a suitable connection to basic paramodulation calculi and thereby shed new light on the connection between different approaches to equational theorem proving.}, } @INPROCEEDINGS{BachmairGanzingerWaldmann-92-alp, AUTHOR = {Bachmair, Leo and Ganzinger, Harald and Waldmann, Uwe}, EDITOR = {Kirchner, H{\'e}l{\`e}ne and Levi, G.}, TITLE = {Theorem proving for hierarchic first-order theories}, BOOKTITLE = {Algebraic and Logic Programming}, PADDRESS = {Berlin, Germany}, ADDRESS = {?}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {632}, YEAR = {1992}, PAGES = {420--434}, NOTE = {Revised version in AAECC, vol.\ 5, number 3/4, pp.\ 193--212, 1994)}, ABSTRACT = {In this work we extend previous results on theorem proving for first-order clauses with equality to hierarchic first-order theories. Semantically such theories are confined to conservative extensions of the base models. It is shown that superposition together with variable abstraction and constraint refutation is refutationally complete for sufficiently complete theories. For the proof we introduce a concept of approximation between theorem proving systems, which makes it possible to reduce the problem to the known case of (flat) first-order theories. These results allow the modular combination of a superposition-based theorem prover with an arbitrary refutational prover for the primitive base theory, whose axiomatic repesentation in some logic may remain hidden.}, } @INPROCEEDINGS{BachmairGanzingerWaldmann-93-kgs, AUTHOR = {Bachmair, Leo and Ganzinger, Harald and Waldmann, Uwe}, EDITOR = {Gottlob, Georg and Leitsch, Alexander and Mundici, Daniele}, TITLE = {Superposition with simplification as a decision procedure for the monadic class with equality}, BOOKTITLE = {Computational Logic and Proof Theory, Third Kurt G{\"o}del Colloquium, KGC'93}, PADDRESS = {Berlin, Germany}, ADDRESS = {Brno, Czech Republic}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {713}, YEAR = {1993}, PAGES = {83--96}, NOTE = {Revised version of Technical Report MPI-I-93-204}, ABSTRACT = {We show that superposition, a restricted form of paramodulation, can be combined with specifically designed simplification rules such that it becomes a decision procedure for the monadic class with equality. The completeness of the method follows from a general notion of redundancy for clauses and superposition inferences.}, } @INPROCEEDINGS{BachmairGanzingerWaldmann-93-lics, AUTHOR = {Bachmair, Leo and Ganzinger, Harald and Waldmann, Uwe}, TITLE = {Set Constraints are the Monadic Class}, BOOKTITLE = {Eighth Annual IEEE Symposium on Logic in Computer Science}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Montreal, Canada}, PUBLISHER = {IEEE}, YEAR = {1993}, PAGES = {75--83}, ABSTRACT = {We investigate the relationship between set constraints and the monadic class of first-order formulas and show that set constraints are essentially equivalent to the monadic class. From this equivalence we can infer that the satisfiability problem for set constraints is complete for NEXPTIME\@. More precisely, we prove that this problem has a lower bound of ${\rm NTIME}(c^{n/\log n})$. The relationship between set constraints and the monadic class also gives us decidability and complexity results for certain practically useful extensions of set constraints, in particular ``negative'' projections and subterm equality tests.}, } @ARTICLE{BachmairGanzingerWaldmann-94-aaecc, AUTHOR = {Bachmair, Leo and Ganzinger, Harald and Waldmann, Uwe}, JOURNAL = {Applicable Algebra in Engineering, Communication and Computing (AAECC)}, TITLE = {Refutational Theorem Proving for Hierarchic First-Order Theories}, ADDRESS = {Berlin, Germany}, NUMBER = {3/4}, PUBLISHER = {Springer}, MONTH = {April}, VOLUME = {5}, ISBN = {0938-1287}, YEAR = {1994}, PAGES = {193--212}, NOTE = {Earlier Version: Theorem Proving for Hierarchic First-Order Theories, in Giorgio Levi and H{\'e}l{\`e}ne Kirchner, editors, {\em Algebraic and Logic Programming, Third International Conference}, LNCS 632, pages 420--434, Volterra, Italy, September 2--4, 1992, Springer-Verlag}, ABSTRACT = {We extend previous results on theorem proving for first-order clauses with equality to hierarchic first-order theories. Semantically such theories are confined to conservative extensions of the base models. It is shown that superposition together with variable abstraction and constraint refutation is refutationally complete for theories that are sufficiently complete with respect to simple instances. For the proof we introduce a concept of approximation between theorem proving systems, which makes it possible to reduce the problem to the known case of (flat) first-order theories. These results allow the modular combination of a superposition-based theorem prover with an arbitrary refutational prover for the primitive base theory, whose axiomatic representation in some logic may remain hidden. Furthermore they can be used to eliminate existentially quantified predicate symbols from certain second-order formulae.}, } @PHDTHESIS{BackesDiss2005, AUTHOR = {Backes, Werner}, TITLE = {{Programmanalyse des XRTL Zwischencodes}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {January}, YEAR = {2005}, } @INPROCEEDINGS{BallPodelskiRajamaniTACAS2000, AUTHOR = {Ball, Thomas and Podelski, Andreas and Rajamani, Sriram K.}, EDITOR = {Margaria, Tiziana and Yi, Wang}, TITLE = {Boolean and Cartesian Abstraction for Model Checking {C} Programs}, BOOKTITLE = {Proceedings of the 7th International Conference on Tools and Algorithms for the Construction and Analysis of Systems (TACAS-2001)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Genova, Italy}, PUBLISHER = {Springer}, MONTH = {April}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2031}, ISBN = {3-540-41865-2}, YEAR = {2001}, PAGES = {268--283}, } @ARTICLE{BarnettBasinHesketh92a, AUTHOR = {Barnett, Richard and Basin, David A. and Hesketh, Jane}, JOURNAL = {Annals of Mathematics and Artificial Intelligence}, TITLE = {A Recursion Planning Analysis of Inductive Completion}, NUMBER = {3/4}, VOLUME = {8}, YEAR = {1993}, PAGES = {363--381}, NOTE = {Also available as Research Report MPI-I-92-230}, ABSTRACT = {We use the AI proof planning techniques of {\it recursion analysis} and {\it rippling} as tools to analyze so-called {\it inductionless induction} proof techniques. Recursion analysis chooses induction schemas and variables and rippling controls rewriting in explicit induction proofs. They provide a basis for explaining the success and failure of inductionless induction, both in deduction of critical pairs and in their simplification. Furthermore, these explicit induction techniques motivate and provide insight into advancements in inductive completion algorithms and suggest directions for further improvements. Our study includes an experimental comparison of Clam, an explicit induction theorem prover, with an implementation of Huet and Hullot's inductionless induction.}, } @BOOK{Barth-95b, AUTHOR = {Barth, Peter}, TITLE = {Logic-based 0-1 constraint programming}, ADDRESS = {Boston, USA}, PUBLISHER = {Kluwer}, MONTH = {November}, SERIES = {Operations Research/Computer Science Interfaces}, ISBN = {0-7923-9663-4}, YEAR = {1995}, PAGES = {272}, ABSTRACT = {A logic view of 0-1 integer programming problems, providing new insights into the structure of problems that can lead the researcher to more effective solution techniques depending on the problem class. Operations research techniques are integrated into a logic programming environment. The first monographic treatment that begins to unify these two methodological approaches. Logic-based methods for modelling and solving combinatorial problems have recently started to play a significant role in both theory and practice. The application of logic to combinatorial problems has a dual aspect. On one hand, constraint logic programming allows one to declaratively model combinatorial problems over an appropriate constraint domain, the problems then being solved by a corresponding constraint solver. Besides being a high-level declarative interface to the constraint solver, the logic programming language allows one also to implement those subproblems that cannot be naturally expressed with constraints. On the other hand, logic-based methods can be used as a constraint solving technique within a constraint solver for combinatorial problems modelled as 0-1 integer programs.}, } @PHDTHESIS{Barth-Diss, AUTHOR = {Barth, Peter}, TITLE = {Logic-based 0-1 Constraint Solving in Constraint Logic Programming}, SCHOOL = {Fachbereich Informatik, Universit{\"a}t des Saarlandes, Germany}, TYPE = {Doctoral dissertation}, MONTH = {February}, YEAR = {1995}, PAGES = {187}, } @INPROCEEDINGS{Barth93b, AUTHOR = {Barth, Peter}, EDITOR = {Voronkov, A.}, TITLE = {Linear 0-1 Inequalities and Extended Clauses}, BOOKTITLE = {Proceedings~4th International~Conference on Logic Programming and Automated Reasoning LPAR '93}, PADDRESS = {Berlin, Germany}, ADDRESS = {St. Petersburg, Russia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {698}, YEAR = {1993}, PAGES = {40--51}, ABSTRACT = {Extended clauses are the basic formulas of the 0-1 constraint solver used in the constraint logic programming language CLP($\cal PB$). We present a method for transforming an arbitrary linear 0-1 inequality into a set of extended clauses, such that the solution space remains invariant. The method relies on cutting planes techniques known from integer programming. We develop special redundancy criteria and can so produce the minimal number of extended clauses. We show how the algorithm can be used to replace the resolution rule in the generalized resolution algorithm for extended clauses. Furthermore the method can be used to obtain all strongest extended cover inequalities of a knapsack inequality.}, } @INPROCEEDINGS{Barth93c, AUTHOR = {Barth, Peter}, EDITOR = {Benhamou, F. and Colmerauer, A. and Smolka, Gert}, TITLE = {A Complete Symbolic 0-1 Constraint Solver}, BOOKTITLE = {3rd Workshop on Constraint Logic Programming (WCLP '93)}, PADDRESS = {Marseille, France}, ADDRESS = {Marseille, France}, PUBLISHER = {Faculty of Luminy}, MONTH = {March}, YEAR = {1993}, ABSTRACT = {We present a complete symbolic 0-1 constraint solver for a system of linear 0-1 inequalities. We give first a method ${\cal T}$ which transforms arbitrary linear 0-1 inequalities into a set $S$ of {\em extended clauses\/} of the form $L1 + \ldots + L_n \geq d$, where the $L_i$ are literals. With the deductive system called {\em generalized resolution\/} (Hooker, 1992) we can then then solve such a set of extended clauses. The solved form is a set of {\em prime\/} extended clauses $\pi(S)$ which has the following key property. If $S$ dominates an extended clause $C$ then there is a single extended clause $D \in \pi(S)$ such that $D$ dominates $C$. Therefore $S$ is insatisfiable iff $0 \geq 1 \in \pi(S)$. So the solved form provides us with an easy test for satisfiability and logical entailment which is useful in the context of constraint logic programming. The basic deduction rules of {\em generalized resolution\/} are a generalization of {\em resolution\/} and {\em diagonal sum\/}. We show how to use the transformation method ${\cal T}$ for implementing these basic deduction rules. For that we use the fact that the rules generate a subset of all possible Gomory rank-1 cuts. We then find a correspondance between these cuts and the result of ${\cal T}$ applied to the linear combination of the involved extended clauses.}, } @INPROCEEDINGS{Barth94a, AUTHOR = {Barth, Peter}, EDITOR = {Jouannaud, Jean-Pierre}, TITLE = {Simplifying Clausal Satisfiability Problems}, BOOKTITLE = {Proceedings of the 1st International Conference on Constraints in Computational Logics (CCL'94)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Munich, Germany}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {845}, YEAR = {1994}, PAGES = {19--33}, ABSTRACT = {Recently linear 0-1 programming methods have been successfully applied to the satisfiability problem of propositional logic. We present a preprocessing method that simplifies the linear 0-1 integer problem corresponding to a clausal satisfiability problem. Valid extended clauses, a generalization of classical clauses, are added to the problem as long as they dominate at least one extended clause of the problem. We describe how to efficiently obtain these valid extended clauses and apply the method to some combinatorial satisfiability problems. The reformulated 0-1 problems contain less but usually stronger 0-1 inequalities and are typically solved much faster than the original one with traditional 0-1 integer programming methods.}, } @INPROCEEDINGS{BarthBockmayr-ICLP95, AUTHOR = {Barth, Peter and Bockmayr, Alexander}, EDITOR = {Sterling, Leon}, TITLE = {Finite domain and cutting plane techniques in {CLP($\cal PB$)}}, BOOKTITLE = {Proceedings of the Twelfth International Conference on Logic Programming}, TYPE = {Proceedings}, PADDRESS = {Cambridge, USA}, ADDRESS = {Shonan Village Center, Hayama-Machi, Kanagawa, Japan}, PUBLISHER = {MIT Press}, SERIES = {Logic Programming}, ISBN = {0-262-69177-9 1061-0464}, YEAR = {1995}, PAGES = {133--147}, ABSTRACT = {Finite domain constraints are one of the most important constraint domains in constraint logic programming. Usually, they are solved by local consistency techniques combined with enumeration. We argue that, in many cases, ensuring local consistency is not enough for both theoretical and practical reasons. We show how to obtain more information from a given constraint set by computing cutting planes and how to use this information in constraint solving and constrained optimization. Focusing on the pseudo-Boolean case \clppb, where all domains are equal to the two-element set $\{0,1\}$, we present specialized cutting plane techniques and illustrate them on a number of examples.}, } @INPROCEEDINGS{BarthBockmayr93a, AUTHOR = {Barth, Peter and Bockmayr, Alexander}, TITLE = {Solving 0-1 Problems in {CLP}({{$\cal PB$}})}, BOOKTITLE = {Proceedings 9th Conference on Artificial Intelligence for Applications ({CAIA})}}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Orlando, FL}, PUBLISHER = {IEEE}, YEAR = {1993}, PAGES = {263--269}, ABSTRACT = {0-1 problems arise in different areas, in particular in artificial intelligence and operations research. For many applications, a simple sub-procedure solving these problems is not sufficient. In this paper, we present the constraint logic programming language CLP(PB) which provides efficient 0-1 constraint solving within the logic programming paradigm. It is well suited for implementing various typical AI problems. CLP(PB) supports pseudo-Boolean constraints, that is equations and inequalities between integer polynomials in 0-1 variables, and pseudo-Boolean optimization, also known as 0-1 programming. We illustrate by example the advantage of pseudo-Boolean formulations versus equivalent ones in propositional logic. We also discuss constraint programming in CLP(PB) and the implementation of algorithms interacting with the current constraint set.}, } @INPROCEEDINGS{BarthBockmayr94, AUTHOR = {Barth, Peter and Bockmayr, Alexander}, TITLE = {Global Consistency in {CLP({{$\cal PB$}})}}, BOOKTITLE = {Proceedings of the 10th Workshop Logic Programming WLP'94}, ADDRESS = {Zurich}, YEAR = {1994}, PAGES = {4}, } @ARTICLE{BarthBockmayr95e, AUTHOR = {Barth, Peter and Bockmayr, Alexander}, JOURNAL = {Computational Logic. The Newsletter of the European Network in Computational Logic}, TITLE = {Pseudo-Boolean Constraint Logic Programming}, NUMBER = {2}, MONTH = {February}, VOLUME = {2}, YEAR = {1995}, PAGES = {52--53}, } @INPROCEEDINGS{BarthBockmayr96a, AUTHOR = {Barth, Peter and Bockmayr, Alexander}, TITLE = {Modelling 0-1 Problems in {CLP({{$\cal PB$}})}}, BOOKTITLE = {Proceedings of the Second International Conference on Practical Application of Constraint Technology}, PADDRESS = {London, UK}, ADDRESS = {London, UK}, PUBLISHER = {The Practical Application Company}, ISBN = {0 9525554 2 5}, YEAR = {1996}, PAGES = {1--9}, ABSTRACT = {Many practical problems involve constraints in 0-1 variables. We apply the constraint logic programming language CLP(PB) to model and reason about 0-1 problems. Given a set of possibly non-linear 0-1 constraints, the solver of CLP(PB) computes an equivalent set of extended clauses. By exploiting the metaprogramming facilities of the logic programming environment, we are able to deal with arbitrary logical conditions between the constraints, in particular with disjunction and implication. At the end, the simplified constraint set is given to an underlying 0-1 constraint solver, which can be either a constraint programming or a mathematical programming system.}, } @INPROCEEDINGS{BarthBockmayr97a, AUTHOR = {Barth, Peter and Bockmayr, Alexander}, TITLE = {{PLAM}: ProLog and Algebraic Modelling}, BOOKTITLE = {Proceedings of the 5th International Conference on the Practical Application of Prolog}, PADDRESS = {London, UK}, ADDRESS = {London, UK}, PUBLISHER = {The Practical Application Company}, ISBN = {0 9525554 5 X}, YEAR = {1997}, PAGES = {73--82}, ABSTRACT = {Algebraic modelling is an important technique in practical applications that require to formulate and to solve a mathematical programming problem. We show how the basic functionality of algebraic modelling systems can be realised very easily in a logic programming system like Prolog. Moreover, we illustrate the additional power of using logic programming in cases where the built-in constructs of traditional modelling languages are not sufficient.}, } @ARTICLE{BarthBockmayr98, AUTHOR = {Barth, Peter and Bockmayr, Alexander}, JOURNAL = {Annals of Operations Research}, TITLE = {Modelling Discrete Optimisation Problems in Constraint Logic Programming}, PUBLISHER = {Baltzer}, VOLUME = {81}, ISBN = {0254-5330}, YEAR = {1998}, PAGES = {467--496}, ABSTRACT = {Constraint logic programming has become a promising new technology for solving complex combinatorial problems. In this paper, we investigate how (constraint) logic programming can support the modelling part when solving discrete optimisation problems. First, we show that the basic functionality of algebraic modelling languages can be realised very easily in a pure logic programming system like Prolog and that, even without using constraints, various additional features are available. Then we focus on the constraint solving facilities offered by constraint logic programming systems. In particular, we explain how the constraint solver of the constraint logic programming language CLP(PB) can be used in modelling 0-1 problems.}, } @INPROCEEDINGS{Basin90b, AUTHOR = {Basin, David A. and Kaufmann, Matt}, EDITOR = {Huet, G{\'e}rard and Plotkin, Gordon}, TITLE = {The Boyer-Moore Prover and Nuprl: An Experimental Comparison}, BOOKTITLE = {Logical Frameworks}, PADDRESS = {Cambridge, UK}, ADDRESS = {?}, PUBLISHER = {Cambridge University Press}, YEAR = {1991}, PAGES = {90--119}, } @INPROCEEDINGS{Basin91a, AUTHOR = {Basin, David A. and Howe, D.}, EDITOR = {Ito, T. and Meyer, A. R.}, TITLE = {Some Normalization Properties of Martin-L{\"o}f's Type Theory, and Applications}, BOOKTITLE = {International Conference on Theoretical Aspects of Computer Software (TACS '91)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Sendai, Japan}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {526}, YEAR = {1991}, PAGES = {475--494}, ABSTRACT = {For certain kinds of applications of type theories, the faithfulness of formalization in the theory depends on intensional, or structural, properties of objects constructed in the theory. For type theories such as LF, such properties can be established via an analysis of normal forms and types. In type theories such as Nuprl or Martin-L\"of's polymorphic type theory, which are much more expressive than LF, the underlying programming language is essentially untyped, and terms proved to be in types do not necessarily have normal forms. Nevertheless, it is possible to show that for Martin-L\"of's type theory, and a large class of extensions of it, a sufficient kind of normalization property does in fact hold in certain well-behaved subtheories. Applications of our results include the use of the type theory as a logical framework in the manner of LF, and an extension of the {\em proofs-as-programs} paradigm to the synthesis of verified computer hardware. For the latter application we point out some advantages to be gained by working in a more expressive type theory.}, } @INPROCEEDINGS{Basin91b, AUTHOR = {Basin, David A. and Giunchiglia, Fausto and Traverso, P.}, EDITOR = {Ardizzone, E. and Gaglio, S. and Sorbello, F.}, TITLE = {Automating Meta-Theory Creation and System Extension}, BOOKTITLE = {Proc. Trends in AI: 2nd Congress of the Italian Association for Artificial Intelligence (AI*IA)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Palermo, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {549}, YEAR = {1991}, PAGES = {48--57}, ABSTRACT = {In this paper we describe a first experiment with a new approach for building theorem provers that can formalize themselves, reason about themselves, and safely extend themselves with new inference procedures. Within the {\tt GETFOL} system we have built a pair of functions that operate between the system's implementation and a theory about this implementation. The first function {\em lifts\/} the actual inference rules to axioms that comprise a theory of {\tt GETFOL}'s inference capabilities. This allows us to turn the prover upon itself whereby we may formally reason about its inference rules and derive new rules. The second function {\em flattens\/} new rules back into the underlying system. This provides a novel means of safe system self-extension and an efficient way of executing derived rules.}, } @ARTICLE{Basin91c, AUTHOR = {Basin, David A. and Brown, G. M. and Leeser, M. E.}, JOURNAL = {Integration: The Intern. Journal of VLSI Design}, TITLE = {Formally Verified Synthesis of Combinational {CMOS} Circuits}, VOLUME = {11}, YEAR = {1991}, PAGES = {235--250}, ABSTRACT = {We present a system for simultaneously synthesizing and proving correct CMOS implementations of combinational circuits. Our system, developed within the Nuprl proof development system, is based on a set of transformation rules that generate CMOS implementations from their logical specifications. Our research differs from previous work in three important ways: our rules are rigorously proven with respect to a formal transistor model, our transformation rules admit the synthesis of both pass transistor and series/parallel networks, and our implementation produces a human readable proof along with each circuit it synthesizes.} } %erg,}, } @INPROCEEDINGS{Basin92a, AUTHOR = {Basin, David A. and Walsh, Toby}, EDITOR = {Kapur, D.}, TITLE = {Difference Matching}, BOOKTITLE = {Proceedings of the11th International Conference on Automated Deduction (CADE-11)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Saragota Springs, NY}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {607}, YEAR = {1992}, PAGES = {295--309}, NOTE = {Also available as Research Report MPI-I-92-211}, ABSTRACT = {Difference matching is a generalization of first-order matching where terms are made identical not only by variable instantiation but also by structure hiding. After matching, the hidden structure may be removed by a type of controlled rewriting, called rippling, that leaves the rest of the term unaltered. Rippling has proved highly successful in inductive theorem proving. Difference matching allows us to use rippling in other contexts, e.g., equational, inequational, and propositional reasoning. We present a difference matching algorithm, its properties, several applications, and suggest extensions.}, } @INCOLLECTION{Basin93a, AUTHOR = {Basin, David A. and Constable, Robert L.}, EDITOR = {Huet, G{\'e}rard and Plotkin, Gordon}, TITLE = {Metalogical Frameworks}, BOOKTITLE = {Logical Environments}, ADDRESS = {Cambridge, UK}, PUBLISHER = {Cambridge University Press}, YEAR = {1993}, PAGES = {1--29}, NOTE = {Also available as Research Report MPI-I-92-205}, ABSTRACT = {In computer science we speak of {\em implementing\/} a logic; this is done in a programming language, such as Lisp, called here the {\em implementation language}. We also reason about the logic, as in understanding how to search for proofs; these arguments are expressed in the {\em metalanguage\/} and conducted in the {\em metalogic\/} of the {\em object language\/} being implemented. We also reason about the implementation itself, say to know it is correct; this is done in a {\em programming logic\/}. How do all these logics relate? This paper considers that question and more. We show that by taking the view that the metalogic is primary, these other parts are related in standard ways. The metalogic should be suitably rich so that the object logic can be presented as an abstract data type, and it must be suitably computational (or constructive) so that an instance of that type is an implementation. The data type abstractly encodes all that is relevant for metareasoning, i.e., not only the term constructing functions but also the principles for reasoning about terms and computing with them. Our work can also be seen as an approach to the task of finding a generic way to present logics and their implementations, which is for example the goal of the Edinburgh Logical Frameworks (ELF) effort. This approach extends well beyond proof-construction and includes computational metatheory as well.}, } @INPROCEEDINGS{Basin93d, AUTHOR = {Basin, David A.}, EDITOR = {Van Hentenryck, Pascal}, TITLE = {{I}sa{W}helk: {W}helk Interpreted in {I}sabelle}, BOOKTITLE = {Proceedings of the 11th International Conference on Logic Programming (ICLP'94)}, PADDRESS = {Cambridge, USA}, ADDRESS = {Santa Margherita Ligure, Italy}, PUBLISHER = {MIT Press}, YEAR = {1994}, PAGES = {741--741}, NOTE = {Paper is extended abstract. {F}ull version available via anonymous ftp to mpi-sb.mpg.de in pub/papers/conferences/Basin-ICLP94.dvi.Z}, ABSTRACT = {The Whelk logic has been proposed as a foundation for logic program synthesis. Here, I interpret the rules of Whelk as rules of first-order logic and derive them in Isabelle. Theoretically, this provides a means to understand the meta-theory behind Whelk, and its correctness. The interpretation suggests simplifications, corrections, and extensions. Practically, it provides a way to construct logic programs from proofs of their correctness by applying the formalized proof rules using higher-order resolution.}, } @INPROCEEDINGS{Basin94a, AUTHOR = {Basin, David A. and Walsh, Toby}, EDITOR = {Bundy, Alan}, TITLE = {Termination Orderings for Rippling}, BOOKTITLE = {Proceedings of the 12th International Conference On Automated Deduction (CADE-12)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Nancy, France}, PUBLISHER = {Springer}, MONTH = {June}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {814}, YEAR = {1994}, PAGES = {466--483}, NOTE = {Also available as Research Report MPI-I-94-209, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken}, ABSTRACT = {Rippling is a special type of rewriting developed for inductive theorem proving. Bundy {\em et.~al.~}have shown that rippling terminates by providing a well-founded order for the annotated rewrite rules used by rippling. Here, we simplify and generalize this order, thereby enlarging the class of rewrite rules that can be used. In addition, we extend the power of rippling by proposing new domain dependent orders. These extensions elegantly combine rippling with more conventional term rewriting. Such combinations offer the flexibility and uniformity of conventional rewriting with the highly goal directed nature of rippling. Finally, we show how our orders simplify implementation of provers based on rippling.}, } @ARTICLE{Basin94c, AUTHOR = {Basin, David A.}, JOURNAL = {Information Processing Letters}, TITLE = {A Term Equality Problem Equivalent to Graph Isomorphism}, NUMBER = {2}, PUBLISHER = {Pergamon Press Ltd}, VOLUME = {51}, ISBN = {0020-0190}, YEAR = {1994}, PAGES = {61--66}, ABSTRACT = {We demonstrate that deciding if two terms containing otherwise uninterpreted associative, commutative, and associative-commutative function symbols and commutative variable-binding operators are equal is polynomially equivalent to determining if two graphs are isomorphic. The reductions we use provide insight into this result and suggest polynomial time special cases.}, } @INCOLLECTION{Basin96c, AUTHOR = {Basin, David A. and Matthews, Se{\'a}n and Vigan{\`o}, Luca}, EDITOR = {Baader, Franz and Schulz, Klaus U.}, TITLE = {A Topography of Labelled Modal Logics}, BOOKTITLE = {Frontiers of Combining Systems (First International Workshop, Munich, March 1996)}, ADDRESS = {Dordrecht, The Netherlands}, PUBLISHER = {Kluwer}, SERIES = {Applied Logic Series}, VOLUME = {3}, YEAR = {1996}, PAGES = {75--92}, ABSTRACT = {Labelled Deductive Systems provide a general method for representing logics in a modular and transparent way. A Labelled Deductive System consists of two parts, a base logic and a labelling algebra, which interact through a fixed interface. The labelling algebra can be viewed as an independent parameter: the base logic stays fixed for a given class of related logics from which we can generate the one we want by plugging in the appropriate algebra. Our work identifies an important property of the structured presentation of logics, their combination, and extension. Namely, there is tension between modularity and extensibility: a narrow interface between the base logic and labelling algebra can limit the degree to which we can make use of extensions to the labelling algebra. We illustrate this in the case of modal logics and apply simple results from proof theory to give examples. }, } @INPROCEEDINGS{Basin96d, AUTHOR = {Basin, David A. and Matthews, Se{\'a}n and Vigan{\`o}, Luca}, EDITOR = {Carlucci-Aiello, Luigia and Doyle, Jon and Shapiro, Stuart}, TITLE = {Implementing Modal and Relevance Logics in a Logical Framework}, BOOKTITLE = {Proceedings of the 5th International Conference on Principles of Knowledge Representation and Reasoning (KR'96)}, PADDRESS = {San Francisco, USA}, ADDRESS = {Cambridge, MA, USA}, PUBLISHER = {Morgan Kaufmann}, YEAR = {1996}, PAGES = {386--397}, ABSTRACT = {We present a framework for machine implementation of both partial and complete fragments of large families of non-classical logics such as modal, relevance, and intuitionistic logics. We decompose a logic into two interacting parts, each a natural deduction system: a base logic of labelled formulae, and a theory of labels characterizing the properties of the Kripke models. Our approach is modular and supports uniform proofs of correctness and proof normalization. We have implemented our work in the Isabelle Logical Framework.}, } @INCOLLECTION{Basin96x, AUTHOR = {Kraan, Ina and Basin, David A. and Bundy, Alan}, EDITOR = {Zhang, Hantao}, TITLE = {Middle-Out Reasoning for Synthesis and Induction}, BOOKTITLE = {Automated mathematical induction}, ADDRESS = {Dordrecht, The Netherlands}, PUBLISHER = {Kluwer}, ISBN = {0-7923-4010-8}, YEAR = {1996}, PAGES = {113--145}, NOTE = {Reprinted from Journal of Automated Reasoning 16 (Nos. 1/2) }, } @INCOLLECTION{Basin96y, AUTHOR = {Basin, David A. and Walsh, Toby}, EDITOR = {Zhang, Hantao}, TITLE = {A Calculus for and Termination of Rippling}, BOOKTITLE = {Automated mathematical induction}, ADDRESS = {Dordrecht, The Netherlands}, PUBLISHER = {Kluwer}, ISBN = {0-7923-4010-8}, YEAR = {1996}, PAGES = {147--180}, NOTE = {Reprinted from Journal of Automated Reasoning 16 (Nos. 1/2) }, } @ARTICLE{Basin97a, AUTHOR = {Basin, David A. and Matthews, Se{\'a}n and Vigan{\`o}, Luca}, JOURNAL = {Journal of Logic and Computation}, TITLE = {Labelled Propositional Modal Logics: Theory and Practice}, NUMBER = {6}, MONTH = {December}, VOLUME = {7}, ISBN = {0955-792X}, YEAR = {1997}, PAGES = {685--717}, ABSTRACT = {We show how labelled deductive systems can be combined with a logical framework to provide a natural deduction implementation of a large and well-known class of propositional modal logics (including K, D, T, B, S4, S4.2, KD45, S5). Our approach is modular and based on a separation between a base logic and a labelling algebra, which interact through a fixed interface. While the base logic stays fixed, different modal logics are generated by plugging in appropriate algebras. This leads to a hierarchical structuring of modal logics with inheritance of theorems. Moreover, it allows modular correctness proofs, both with respect to soundness and completeness for semantics, and faithfulness and adequacy of the implementation. We also investigate the tradeoffs in possible labelled presentations: we show that a narrow interface between the base logic and the labelling algebra supports modularity and provides an attractive proof-theory but limits the degree to which we can make use of extensions to the labelling algebra.}, } @ARTICLE{Basin97b, AUTHOR = {Basin, David A. and Matthews, Se{\'a}n and Vigan{\`o}, Luca}, JOURNAL = {Journal of Logic, Language and Information}, TITLE = {Labelled Modal Logics: quantifiers}, NUMBER = {3}, PUBLISHER = {Kluwer}, VOLUME = {7}, ISBN = {0925-8531}, YEAR = {1998}, PAGES = {237--263}, ABSTRACT = {In previous work we gave an approach, based on labelled natural deduction, for formalizing proof systems for a large class of propositional modal logics that includes K, D, T, B, S4, S4.2, KD45 and S5. Here we extend this approach to quantified modal logics, providing formalizations for logics with varying, increasing, decreasing, or constant domains. The result is modular with respect to both properties of the accessibility relation in the Kripke frame and the way domains of individuals change between worlds. Our approach has a modular metatheory too; soundness, completeness and normalization are proved uniformly for every logic in our class. Finally, our work leads to a simple implementation of a modal logic theorem prover in a standard logical framework.}, } @ARTICLE{Basin97c, AUTHOR = {Basin, David A. and Matthews, Se{\'a}n and Vigan{\`o}, Luca}, JOURNAL = {Studia Logica}, TITLE = {Natural Deduction for Non-Classical Logics}, NUMBER = {1}, PUBLISHER = {Kluwer}, VOLUME = {60}, ISBN = {0039-3215}, YEAR = {1998}, PAGES = {119--160}, ABSTRACT = {We present a framework for machine implementation of families of non-classical logics with Kripke-style semantics. We decompose a logic into two interacting parts, each a natural deduction system: a base logic of labelled formulae, and a theory of labels characterizing the properties of the Kripke models. By appropriate combinations we capture both partial and complete fragments of large families of non-classical logics such as modal, relevance, and intuitionistic logics. Our approach is modular and supports uniform proofs of soundness, completeness and proof normalization. We have implemented our work in the Isabelle Logical Framework.}, } @INPROCEEDINGS{Basin97d, AUTHOR = {Basin, David A. and Matthews, Se{\'a}n and Vigan{\`o}, Luca}, EDITOR = {Gottlob, G. and Leitsch, A. and Mundici, D.}, TITLE = {A New Method for Bounding the Complexity of Modal Logics}, BOOKTITLE = {Proceedings of the 5th Kurt G{\"o}del Colloquium on Computational Logic and Proof Theory (KGC-97)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Vienna, Austria}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1289}, ISBN = {3-540-63385-5}, YEAR = {1997}, PAGES = {89--102}, ABSTRACT = {We present a new proof-theoretic approach to bounding the complexity of the decision problem for propositional modal logics. We formalize logics in a uniform way as sequent systems and then restrict the structural rules for particular systems. This, combined with an analysis of the accessibility relation of the corresponding Kripke structures, yields decision procedures with bounded space requirements. As examples we give O(n log n) procedures for the modal logics K and T.}, } @INPROCEEDINGS{Basin98a, AUTHOR = {Basin, David A. and Matthews, Se{\'a}n and Vigan{\`o}, Luca}, EDITOR = {Ginzburg, Jonathan and Khasidashvili, Zurab and Vogel, Carl and Levy, Jean-Jacques and Vallduvi, Enric}, TITLE = {A Modular Presentation of Modal Logics in a Logical Framework}, BOOKTITLE = {Proceedings of the 1st Tbilisi Symposium on Language, Logic and Computation: Selected Papers}, ORGANIZATION = {folli}, PADDRESS = {Stanford, USA}, ADDRESS = {Tbilisi, Georgia}, PUBLISHER = {CSLI}, SERIES = {Studies in Logic, Langugage and Information}, ISBN = {1-5786-099-6}, YEAR = {1998}, PAGES = {293--307}, ABSTRACT = {We present a theoretical and practical approach to the modular natural deduction presentation of modal logics and their implementation in a logical framework. Our work treats a large and well-known class of modal logics (including $K$, $KD$, $T$, $B$, $S4$, $S4.2$, $S5$) in a uniform way with respect to soundness and completeness for semantics, and faithfulness and adequacy of the implementation. Moreover, it results in a pleasingly simple and usable implementation of these logics.}, } @INPROCEEDINGS{BasinAbdu95, AUTHOR = {Ayari, Abdelwaheb and Basin, David A.}, EDITOR = {Paulson, Lawrence C.}, TITLE = {Interpretation of the Deductive Tableau in {HOL}}, BOOKTITLE = {Proceedings of the First Isabelle Users Workshop}, TYPE = {Technical Report}, PADDRESS = {Cambridge}, ADDRESS = {University of Cambridge, England}, NUMBER = {379}, PUBLISHER = {University of Cambridge}, MONTH = {September}, YEAR = {1995}, PAGES = {91--100}, } @ARTICLE{BasinAnderson00, AUTHOR = {Anderson, Penny and Basin, David A.}, JOURNAL = {Journal of Symbolic Computation}, TITLE = {Program Development Schemata as Derived Rules}, ADDRESS = {London, UK}, NUMBER = {1}, PUBLISHER = {Academic Press}, VOLUME = {30}, ISBN = {0747-7171}, YEAR = {2000}, PAGES = {5--36}, ABSTRACT = {We show how the formalization and application of schemata for program development can be reduced to the formalization and application of derived rules of inference. We formalize and derive schemata as rules in theories that axiomatize program data and programs themselves. We reduce schema-based program development to ordinary theorem proving, where higher-order unification is used to apply rules. Conceptually, our formalization is simple and unifies divergent views of schemata, program synthesis, and program transformation. Practically, our formalization yields a simple methodology for carrying out development using existing logical frameworks; we illustrate this in the domain of logic program synthesis and transformation using the Isabelle logical framework.}, } @INPROCEEDINGS{BasinBundyKraanMatthews93c, AUTHOR = {Basin, David A. and Bundy, Alan and Kraan, Ina and Matthews, Se{\'a}n}, TITLE = {A Framework for Program Development Based on Schematic Proof}, BOOKTITLE = {Proc. 7th Intern.~Workshop on Software Specification and Design}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Redondo Beach, CA}, PUBLISHER = {IEEE}, YEAR = {1993}, PAGES = {162--171}, NOTE = {Also available as Research Report MPI-I-93-231}, ABSTRACT = {Often, calculi for manipulating and reasoning about programs can be recast as calculi for synthesizing programs. The difference involves often only a slight shift of perspective: admitting metavariables into proofs. We propose that such calculi should be implemented in logical frameworks that support this kind of proof construction and that such an implementation can unify program verification and synthesis. Our proposal is illustrated with a worked example developed in Paulson's Isabelle system. We also give examples of existent calculi that are closely related to the methodology we are proposing and others that can be profitably recast using our approach.}, } @INPROCEEDINGS{BasinFriedrich96, AUTHOR = {Basin, David A. and Friedrich, Stefan}, EDITOR = {von Wright, J. and Grundy, J. and Harrison, J.}, TITLE = {Modeling a hardware synthesis methodology in {I}sabelle}, BOOKTITLE = {Theorem Proving in Higher Order Logics. 9th International Conference, TPHOLs'96}, ORGANIZATION = {Turku Centre for Comput. Sci.; Res. Inst. Found. Abo Acad.; Acad. Finland}, PADDRESS = {Berlin, Germany}, ADDRESS = {Turku, Finland}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1125}, ISBN = {3540615873}, YEAR = {1996}, PAGES = {33--50}, ABSTRACT = {Formal synthesis is a methodology developed at Kent for combining circuit design and verification. We have reinterpreted this methodology in ISABELLE's theory of higher-order logic so that circuits are synthesized using higher-order resolution. Our interpretation simplifies and extends formal synthesis both conceptually and in implementation. It also supports integration of this development style with other synthesis methodologies and leads to techniques for developing new classes of circuits, e.g., recursive descriptions of parameterized circuits.}, } @ARTICLE{BasinFriedrichVeritas, AUTHOR = {Basin, David A. and Friedrich, Stefan}, JOURNAL = {Formal Methods in Systems Design}, TITLE = {Modeling a Hardware Synthesis Methodology in {I}sabelle}, NUMBER = {2}, MONTH = {September}, VOLUME = {15}, YEAR = {1999}, PAGES = {99--122}, ABSTRACT = {Formal Synthesis is a methodology developed at Kent for combining circuit design and verification, where a circuit is constructed from a proof that it meets a given formal specification. We have reinterpreted this methodology in Isabelle's theory of higher-order logic so that circuits are incrementally built during proofs using higher-order resolution. Our interpretation simplifies and extends Formal Synthesis both conceptually and in implementation. It also supports integration of this development style with other proof-based synthesis methodologies and leads to techniques for developing new classes of circuits, e.g., recursive descriptions of parametric designs.}, } @ARTICLE{BasinGanzinger-01-jacm, AUTHOR = {Basin, David A. and Ganzinger, Harald}, JOURNAL = {Journal of the ACM}, TITLE = {Automated Complexity Analysis Based on Ordered Resolution}, ADDRESS = {New York, USA}, NUMBER = {1}, PUBLISHER = {ACM}, VOLUME = {48}, YEAR = {2001}, PAGES = {70--109}, ABSTRACT = {We define order locality to be a property of clauses relative to a term ordering. This property is a kind of generalization of the subformula property for proofs where the terms appearing in proofs can be bounded, under the given ordering, by terms appearing in the goal clause. We show that when a clause set is order local, then the complexity of its ground entailment problem is a function of its structure (e.g., full versus Horn clauses), and the ordering used. We prove that, in many cases, order locality is equivalent to a clause set being saturated under ordered resolution. This provides a means of using standard resolution theorem provers for testing order locality and transforming non-local clause sets into local ones. We have used the Saturate system to automatically establish complexity bounds for a number of nontrivial entailment problems relative to complexity classes which include polynomial and exponential time and co-NP.}, } @INPROCEEDINGS{BasinGanzinger96a, AUTHOR = {Basin, David A. and Ganzinger, Harald}, TITLE = {Complexity Analysis Based on Ordered Resolution}, BOOKTITLE = {Proceedings of the 11th Annual IEEE Symposium on Logic in Computer Science (LICS'96)}, ORGANIZATION = {IEEE Comput. Soc. Tech. Committee on Math. Found. Comput.; ACM Special Interest Group on Automata \& Comput. Theory; Assoc. Symbolic Logic; Eur. Assoc. Theoret. Comput. Sci}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {New Brunswick, New Jersey, USA}, PUBLISHER = {IEEE}, ISBN = {0818674636}, YEAR = {1996}, PAGES = {456--465}, ABSTRACT = {We define \emph{order locality} to be a property of clauses relative to a term ordering. This property is a kind of generalization of the subformula property for proofs where terms arising in proofs are bounded, under the given ordering, by terms appearing in the goal clause. We show that when a clause set is order local, then the complexity of its ground entailment problem is a function of its structure (e.g., full versus Horn clauses), and the ordering used. We prove that, in many cases, order locality is equivalent to a clause set being saturated under ordered resolution. This provides a means of using standard resolution theorem provers for testing order locality and transforming non-local clause sets into local ones. We have used the Saturate system to automatically establish complexity bounds for a number of nontrivial entailment problems relative to complexity classes which include polynomial and exponential time and co-NP.}, } @PHDTHESIS{BasinHabil1995, AUTHOR = {Basin, David A.}, TITLE = {Thema der Antrittsvorlesung: MONA - Ein Werkzeug zur Systemverifikation und -entwicklung}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Habilitation thesis}, MONTH = {June}, YEAR = {1995}, ABSTRACT = {Techniken auf der Grundlage bin{\"a}rer Entscheidungsdiagramme (BDDs) haben sich bei der Analyse endlicher Funktionen und Systeme als n{\"u}tzlich erwiesen, z.B. bei der {\"A}quivalenz von Schaltkreisentw{\"u}rfen. Jedoch sind diese Methoden f{\"u}r die Analyse unendlicher Zustandsr{\"a}ume nicht geeignet. Ich stelle MONA vor, ein logikbasiertes Werkzeug, das als Erweiterung dieser BDD-Methoden f{\"u}r parametrisierte Entw{\"u}rfe in unendlichen Zustandsr{\"a}umen betrachtet werden kann. Zum Beispiel kann MONA benutzt werden, um automatish die Korrektheit einer (in der Zahl der Eingabebits) parametrisierten arithmetisch-logischen Einheit (ALU) zu beweisen. Dar{\"u}berhinaus zeige ich, wie man diskrete Zeit als Parameter betrachten und MONA dazu benutzen kann, bei zeitabh{\"a}ngigen Spezifikationen und Protokollen Schl{\"u}sse zu ziehen und Fehler zu entdecken.}, } @INPROCEEDINGS{BasinKlarlund95, AUTHOR = {Basin, David A. and Klarlund, Nils}, TITLE = {Hardware Verification using Monadic Second-Order Logic}, BOOKTITLE = {Proceedings of the 7th International Conference on Computer-Aided Verification (CAV '95)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Liege, Belgium}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {939}, YEAR = {1995}, PAGES = {31--41}, } @ARTICLE{BasinKlarlund98, AUTHOR = {Basin, David A. and Klarlund, Nils}, JOURNAL = {Formal Methods in Systems Design}, TITLE = {Automata Based Symbolic Reasoning in Hardware Verification}, NUMBER = {3}, MONTH = {November}, VOLUME = {13}, YEAR = {1998}, PAGES = {255--288}, ABSTRACT = {We present a new approach to hardware verification based on describing circuits in Monadic Second-order Logic (MSL). We show how to use this logic to represent generic designs like $n$-bit adders, which are parameterized in space, and sequential circuits, where time is an unbounded parameter. MSL admits a decision procedure, implemented in the MONA tool, which reduces formulas to canonical automata. The decision problem for MSL is non-elementary decidable and thus unlikely to be usable in practice. However, we have used MONA to automatically verify, or find errors in, a number of circuits studied in the literature. Previously published machine proofs of the same circuits are based on deduction and may involve substantial interaction with the user. Moreover, our approach is orders of magnitude faster for the examples considered. We show why the underlying computations are feasible and how our use of MONA generalizes standard BDD-based hardware reasoning.}, } @INPROCEEDINGS{BasinLOPSTR94, AUTHOR = {Basin, David A.}, EDITOR = {Fribourg, Laurent and Turini, Franco}, TITLE = {Logic Frameworks for Logic Programs}, BOOKTITLE = {Proceedings of the 4th International Workshop on Logic Program Synthesis and Transformation - Meta Programming in Logic (LOPSTR'94 and META'94)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Pisa, Italy}, PUBLISHER = {Springer}, MONTH = {June}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {883}, YEAR = {1994}, PAGES = {1--16}, NOTE = {Also available as Research Report MPI-I-94-218, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken}, } @INPROCEEDINGS{BasinMatthews93d, AUTHOR = {Basin, David A. and Matthews, Se{\'a}n}, EDITOR = {Shyamasundar, R. K.}, TITLE = {A Conservative Extension of First-Order Logic and its Applications to Theorem Proving}, BOOKTITLE = {Proceedings of the 13th Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS'93)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Bombay, India}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {761}, YEAR = {1993}, PAGES = {151--160}, NOTE = {Also available as Research Report MPI-I-93-235}, ABSTRACT = {We define a weak second-order extension of first-order logic. We prove a second-order cut elimination theorem for this logic and use this to prove a conservativity and a realisability result. We give applications to formal program development and theorem proving, in particular, in modeling techniques in formal metatheory.}, } @ARTICLE{BasinMatthews96a, AUTHOR = {Basin, David A. and Matthews, Se{\'a}n}, JOURNAL = {Journal of Logic and Computation}, TITLE = {Adding Metatheoretic facilities to First-order Theories}, NUMBER = {6}, PUBLISHER = {Oxford University Press}, VOLUME = {6}, ISBN = {0955-792X}, YEAR = {1996}, PAGES = {835--849}, ABSTRACT = {Generic proof systems like Isabelle provide some limited but useful metatheoretic facilities for declared logics; in particular, users can prove simple derived rules and also `solve' formulae that contain metavariables - a technique useful for program synthesis. We show how an arbitrary first-order theory can be conservatively extended to provide similar facilities, without a supporting metatheory, and examine what the limitations of this approach are.}, } @INPROCEEDINGS{BasinMatthews96b, AUTHOR = {Basin, David A. and Matthews, Se{\'a}n}, EDITOR = {McRobbie, M. A. and Slaney, J. K.}, TITLE = {Structuring metatheory on inductive definitions}, BOOKTITLE = {Proceedings of the 13th International Conference on Automated Deduction (CADE-13)}, TYPE = {Full Conference Paper}, PADDRESS = {Berlin, Germany}, ADDRESS = {New Brunswick, New Jersey, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1104}, ISBN = {3540615113}, YEAR = {1996}, PAGES = {171--185}, ABSTRACT = {We examine a problem in formal metatheory: if theories are structured hierarchically, there are metatheorems which hold in only some extensions. We illustrate this using modal logics and the deduction theorem. We show how statements of metatheorems in such hierarchies can take account of possible theory extensions; i.e., a metatheorem formalizes not only the theory in which it holds, but also under what extensions, both to the language and proof system, it remains valid. We show that FS/sub 0/, a system for formal metamathematics, provides a basis for organizing theories this way, and we report on our practical experience }, } @ARTICLE{BasinMatthews98a, AUTHOR = {Matthews, Se{\'a}n and Basin, David A.}, JOURNAL = {Information and Computation}, TITLE = {Structuring Metatheory on Inductive Definitions}, ADDRESS = {London, UK}, NUMBER = {1/2}, PUBLISHER = {Academic Press}, VOLUME = {162}, ISBN = {0890-5401}, YEAR = {2000}, PAGES = {80--95}, ABSTRACT = {We examine a problem for machine supported metatheory. There are statements true about a theory that are true of some (but only some) extensions; however standard theory-structuring facilities do not support selective inheritance. We use the example of the deduction theorem for modal logic and show how a statement about a theory can explicitly formalize the closure conditions extensions should satisfy for it to remain true. We show how metatheories based on inductive definitions allow theories and general metatheorems to be organized hierarchically this way, and report on a case study using the theory FS0.}, } @ARTICLE{BasinMatthews98b, AUTHOR = {Matthews, Se{\'a}n and Basin, David A.}, JOURNAL = {Electronic Notes in Computer Science}, TITLE = {Scoped Metatheorems}, ADDRESS = {Amsterdam, the Netherlands}, PUBLISHER = {Elsevier}, VOLUME = {15}, YEAR = {1998}, PAGES = {1--14}, } @INCOLLECTION{BasinMatthewsHPL, AUTHOR = {Basin, David A. and Matthews, Sean}, EDITOR = {Gabbay, Dov and Guenthner, Franz}, TITLE = {Logical Frameworks}, BOOKTITLE = {Handbook of Philosophical Logic}, ADDRESS = {Dordrecht, The Netherlands}, PUBLISHER = {Reidel}, EDITION = {second edition}, VOLUME = {9}, ISBN = {1-4020-0699-3}, YEAR = {2002}, PAGES = {89--164}, } @INPROCEEDINGS{BasinMatthewsVigano97c, AUTHOR = {Basin, David A. and Matthews, Se{\'a}n and Vigan{\`o}, Luca}, EDITOR = {Brewka, Gerhard and Habel, Christopher and Nebel, Bernhard}, TITLE = {Labelled quantified modal logics}, BOOKTITLE = {Proceedings of the 21st Annual German Conference on Artificial Intelligence (KI-97): Advances in Artificial Intelligence}, PADDRESS = {Berlin, Germany}, ADDRESS = {Freiburg, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1303}, ISBN = {3-540-63493-2}, YEAR = {1997}, PAGES = {171--182}, ABSTRACT = {We present an approach to providing natural deduction style proof systems for a large class of quantified modal logics with varying, increasing, decreasing or constant domains of quantification. The systems we develop are modular both in the behavior of the accessibility relation and quantification relative to the semantics, and in the proofs of soundness and completeness relative to that semantics. Our systems also provide the basis of simple implementations of quantified modal logics in a standard logical framework theorem prover.}, } @TECHREPORT{BasinMeta, EDITOR = {Basin, David A. and Giunchiglia, Fausto and Kaufmann, Matt}, TITLE = {Proceedings of the Workshop on Correctness and Metatheoretic Extensibility of Automated Reasoning Systems}, INSTITUTION = {Istituto Per La Ricerca Scientifica E Tecnologica}, TYPE = {Technical Report}, ADDRESS = {Povo}, NUMBER = {9405-10}, YEAR = {1994}, } @ARTICLE{BasinTTRewrite, AUTHOR = {Basin, David A.}, JOURNAL = {Journal of Information Processing and Cybernetics}, TITLE = {Generalized Rewriting in Type Theory}, NUMBER = {5/6}, VOLUME = {30}, YEAR = {1994}, PAGES = {249--259}, NOTE = {erschienen 1995 !!!}, } @INPROCEEDINGS{BasinWalsh93b, AUTHOR = {Basin, David A. and Walsh, Toby}, EDITOR = {Bajcsy, R.}, TITLE = {Difference Unification}, BOOKTITLE = {Proceedings of the 13th International Joint Conference on Artificial Intelligence (IJCAI-93)}, PADDRESS = {San Mateo, CA}, ADDRESS = {Chambery, France}, PUBLISHER = {Morgan Kaufmann}, VOLUME = {1}, YEAR = {1993}, PAGES = {116--122}, NOTE = {Also available as Research Report MPI-I-92-247}, ABSTRACT = {We extend previous work on difference identification and reduction as a technique for automated reasoning. We generalize unification so that terms are made equal not only by finding substitutions for variables but also by hiding term structure. This annotation of structural differences serves to direct rippling, a kind of rewriting designed to remove structural differences in a controlled way. On the technical side, we give a rule-based algorithm for difference unification, and analyze its correctness, completeness, and complexity. On the practical side, we present a novel search strategy (called left-first search) for applying these rules in an efficient way. Finally, we show how this algorithm can be used in new ways to direct rippling and how it can play an important role in theorem proving and other kinds of automated reasoning.}, } @ARTICLE{BasinWalshJAR96, AUTHOR = {Basin, David A. and Walsh, Toby}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {A Calculus for and Termination of Rippling}, NUMBER = {1/2}, PUBLISHER = {Kluwer}, VOLUME = {16}, ISBN = {0168-7433}, YEAR = {1996}, PAGES = {147--180}, ABSTRACT = {Rippling is a type of rewriting developed for inductive theorem proving that uses annotations to direct search. In this paper we give a new and more general formalization of rippling. We introduce a simple calculus for rewriting annotated terms, close in spirit to first-order rewriting, and prove that it has the formal properties desired of rippling. We then develop the criteria for proving the termination of such annotated rewriting, and introduce orders on annotated terms that lead to termination. In addition, we show how to make rippling more flexible by adapting the termination orders to the problem domain. Our work has practical as well as theoretical advantages: it has led to a very simple implementation of rippling that has been integrated in the Edinburgh CLAM system.}, } @MASTERSTHESIS{Baumeister1990, AUTHOR = {Baumeister, Hubert}, TITLE = {{{\"U}ber die Stabilit{\"a}t parameterisierter algebraischer Spezifikationen}}, SCHOOL = {Universit{\"a}t Dortmund}, TYPE = {Master's thesis}, MONTH = {July}, YEAR = {1990}, } @INPROCEEDINGS{Baumeister91a, AUTHOR = {Baumeister, Hubert}, EDITOR = {Abramsky, S. and Maibaum, T. S. E.}, TITLE = {Unifying Initial and Loose Semantics of Parameterized Specifications in an Arbitrary Institution}, BOOKTITLE = {Proceedings of the International Joint Conference on Theory and Practice of Software Development (TAPSOFT '91)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Brighton, UK}, PUBLISHER = {Springer}, MONTH = {April}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {493}, YEAR = {1991}, PAGES = {103--120}, ABSTRACT = {In this paper we are going to present a theory of parameterized abstract datatypes as the model-theoretic level of parameterized specifications. We will show that parameterized abstract datatypes allow us to model the main approaches to the semantics of parameterized specifications, the loose approach and the free functor semantics, using the same formalism. As a consequence we obtain that, when using data constraints in a specification language, this language is able to cope with both the loose and the free functor semantics at the same time. To be independent of a specific logic this theory is developed in the context of an arbitrary institution.}, } @INPROCEEDINGS{Baumeister95, AUTHOR = {Baumeister, Hubert}, EDITOR = {Mosses, Peter D. and Nielsen, Mogens and Schwartzbach, Michael I.}, TITLE = {Relations as Abstract Datatypes: An Institution to Specify Relations between Algebras}, BOOKTITLE = {Proceedings of the 6th Joint Conference on Theory and Practice of Software Development (TAPSOFT '95)}, PADDRESS = {Berlin, Germany}, ADDRESS = {{\AA}rhus, Denmark}, PUBLISHER = {Springer}, MONTH = {May}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {915}, YEAR = {1995}, PAGES = {756--771}, ABSTRACT = {One way to model the execution state of an imperative program is as a many sorted algebra. Program variables are modeled by functions and their types by sorts. The execution of a program is modeled by a relation between the states of the program (algebras) before and after the execution of the program. There are several methods to specify such relations between algebras. One method is to use specifications in the style of Z, VDM-SL or Larch. Specifications in Z of relations between states are first order formulas over the value of the variables comprising the state before and after an operation. In this paper we shall define an institution for the specification of relations between structures of some base institution (eg.\ the institution of equational logic or first order predicate logic). Sets of structures over a common signature, abstract datatypes, in this institution denote relations between structures of the base institution. This makes it possible to apply a rich repertoire of already existent techniques for specifying abstract datatypes, which can be found for example in the work of Goguen and Burstall, Sannella, Wirsing and Tarlecki, Ehrig, Pepper and Orejas and others, to the specification of relations. This paper tries to narrow the gap between algebraic specification languages like Clear, ASL or Act-One and model theoretic based specification languages like Z, VDM-SL or the Larch Interface language.}, } @PHDTHESIS{BaumeisterDiss99, AUTHOR = {Baumeister, Hubert}, TITLE = {Relations between Abstract Datatypes modeled as Abstract Datatypes}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {November}, YEAR = {1999}, ABSTRACT = {In this thesis we define a framework for the specification of dynamic behavior of software systems. This framework is motivated by the state as algebra approach and the model-oriented language Z. From the state as algebra approach we use the idea of modeling the environment and the state components as structures of an institution. However, in contrast to the state as algebra approach, states in our framework are modeled by structures from any suitable institution not only those having of algebras as their structures. From Z we use the idea that environment, state spaces and relations between state spaces are specified using the same logic and how more complex relations can be constructed from simpler ones by means of the schema calculus. However, we differ from Z in that our framework can be instantiated by different institutions, while the approach of Z can only work because of the particular logical system used by Z.}, } @UNPUBLISHED{BaumgartnerSuchanek2005, AUTHOR = {Baumgartner, Peter and Suchanek, Fabian}, TITLE = {Model-Generation Theorem Proving for First-Order Logic Ontologies}, YEAR = {2005}, PAGES = {30}, ABSTRACT = {Formal ontologies play an increasingly important role in demanding knowledge representation applications like the {\em Semantic Web\/}. Automated reasoning support for these ontologies is mandatory for tasks like debugging, classifying or querying the knowledge bases, and description logic (DL) reasoners have been shown to be very effective for that. Yet, as language extensions beyond (decidable) DLs are being discussed, more general first-order logic systems are required, too. In this paper, we pursue this direction and consider automated reasoning on full first-order logic knowledge bases. We put forward an optimized approach of transforming such knowledge bases to clause logic. The transformations include a Brand-like transformation to eliminate equality, and a transformation that incorporates a {\em blocking\/} technique to ``checks loops'' in derivations. The latter transformation lets theorem provers terminate more often on satisfiable input formulas. It thus enables more robust automated reasoning support on ontologies, where disproving is a common task. While the transformations are applicable to any clause set, we concentrate in this paper on demonstrating their effectiveness on a standard test suite devised by the Semantic Web community.}, } @INPROCEEDINGS{Baumgartner:Burchardt:LPFrameNet:JELIA:2004, AUTHOR = {Baumgartner, Peter and Burchardt, Aljoscha}, EDITOR = {Alferes, Jos{\'e} J{\'u}lio and Leite, João}, TITLE = {Logic Programming Infrastructure for Inferences on {FrameNet}}, BOOKTITLE = {Logics in artificial intelligence : 9th European Conference, JELIA 2004}, PADDRESS = {Berlin}, ADDRESS = {Lisbon, Portugal}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {3229}, ISBN = {3-540-23242-7}, YEAR = {2004}, PAGES = {591--603}, } @ARTICLE{Baumgartner:etal:AR-KR-Management:KI:2005, AUTHOR = {Baumgartner, Peter and Furbach, Ulrich and Yahya, Adnan}, JOURNAL = {KI - K{\"u}nstliche Intelligenz}, TITLE = {Automated Reasoning, Knowledge Representation and Management}, ADDRESS = {Bremen, Germany}, PUBLISHER = {B{\"o}ttcher IT}, VOLUME = {1}, ISBN = {0933-1875}, YEAR = {2005}, PAGES = {5--11}, ABSTRACT = {This overview discusses the connection between two subdisciplines of AI, Automated Reasoning and Knowledge Representation. The state of the art in Automated Reasoning is briefly indicated and its relation to Logic Programming and Knowledge Representation is presented. The issue of Knowledge Management is addressed via a case study.}, } @INPROCEEDINGS{Baumgartner:etal:Darwin:ESFOR:2004, AUTHOR = {Baumgartner, Peter and Fuchs, Alexander and Tinelli, Cesare}, EDITOR = {Schulz, Stephan and Tammet, Tanel and Sutcliffe, Geoff}, TITLE = {Darwin: A Theorem Prover for the Model Evolution Calculus}, BOOKTITLE = {Proceedings of the 1st Workshop on Empirically Successful First Order Reasoning (ESFOR'04)}, PADDRESS = {Cork, Ireland}, ADDRESS = {Cork, Ireland}, PUBLISHER = {UCC}, SERIES = {IJCAR 2004 Workshop Proceedings}, YEAR = {2004}, PAGES = {1--24}, } @ARTICLE{Baumgartner:etal:Darwin:IJAIT:2006, AUTHOR = {Baumgartner, Peter and Fuchs, Alexander and Tinelli, Cesare}, JOURNAL = {International Journal on Artificial Intelligence Tools}, TITLE = {Implementing the Model Evolution Calculus}, NUMBER = {1}, PUBLISHER = {World Scientific}, VOLUME = {15}, ISBN = {0218-2130}, YEAR = {2006}, PAGES = {21--52}, ABSTRACT = {Darwin is the first implementation of the Model Evolution Calculus by Baumgartner and Tinelli. The Model Evolution Calculus lifts the DPLL procedure to first-order logic. Darwin is meant to be a fast and clean implementation of the calculus, showing its effectiveness and providing a base for further improvements and extensions. Based on a brief summary of the Model Evolution Calculus, we describe in the main part of the paper Darwin's proof procedure and its data structures and algorithms, discussing the main design decisions and features that influence Darwin's performance. We also report on practical experiments carried out with problems from the CASC-J2 system competition and parts of the TPTP Problem Library, and compare the results with those of other state-of-the-art theorem provers.}, } @ARTICLE{Baumgartner:etal:in2math:swtechnik:2004, AUTHOR = {Baumgartner, Peter and Grabowski, Barbara and Oevel, Walter and Melis, Erica}, JOURNAL = {Softwaretechnik-Trends}, TITLE = {{In2Math - Interaktive Mathematik- und Informatikgrundausbildung}}, ADDRESS = {Bonn}, NUMBER = {1}, PUBLISHER = {GI}, VOLUME = {24}, ISBN = {0720-8928}, YEAR = {2004}, PAGES = {36--45}, } @ARTICLE{Baumgartner:EtAl:LivingBook:JAR:2004, AUTHOR = {Baumgartner, Peter and Furbach, Ulrich and Gross-Hardt, Margret and Sinner, Alex}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {Living Book -- Deduction, Slicing, and Interaction}, NUMBER = {3}, PUBLISHER = {Kluwer}, VOLUME = {32}, YEAR = {2004}, PAGES = {259--286}, } @INPROCEEDINGS{Baumgartner:etal:ModelBasedSchemaReasoning:KI:2004, AUTHOR = {Baumgartner, Peter and Furbach, Ulrich and Gross-Hardt, Margret and Kleemann, Thomas}, EDITOR = {Biundo, Susanne and Fr{\"u}hwirth, Thom and Palm, G{\"u}nther}, TITLE = {Model Based Deduction for Database Schema Reasoning}, BOOKTITLE = {KI 2004: Advances in Artificial Intelligence: 27th Annual German Conference on AI, KI 2004}, PADDRESS = {Berlin, Germany}, ADDRESS = {Ulm, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {3238}, ISBN = {3-540-23166-8}, YEAR = {2004}, PAGES = {168--182}, ABSTRACT = {We aim to demonstrate that automated deduction techniques, in particular those following the model computation paradigm, are very well suited for database schema/query reasoning. Specifically, we present an approach to compute completed paths for database or XPath queries. The database schema and a query are transformed to disjunctive logic programs with default negation, using a description logic as an intermediate language. Our underlying deduction system, KRHyper, then detects if a query is satisfiable or not. In case of a satisfiable query, all completed paths – those that fulfill all given constraints – are returned as part of the computed models. The purpose of computing completed paths is to reduce the workload on a query processor. Without the path completion, a usual XPath query processor would search the whole database for solutions to the query, which need not be the case when using completed paths instead. We understand this paper as a first step, that covers a basic schema/query reasoning task by model-based deduction. Due to the underlying expressive logic formalism we expect our approach to easily adapt to more sophisticated problem settings, like type hierarchies as they evolve within the XML world.}, } @INCOLLECTION{Baumgartner:Furbach:LivingBooksStrangeThings:JS60:2004, AUTHOR = {Baumgartner, Peter and Furbach, Ulrich}, EDITOR = {Hutter, Dieter and Stephan, Werner}, TITLE = {Living Books, Automated Deduction and other Strange Things}, BOOKTITLE = {Mechanizing Mathematical Reasoning: Techniques, Tools and Applications - Essays in honour of J{\"o}rg H. Siekmann}, ADDRESS = {New York, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2605}, ISBN = {0302-9743}, YEAR = {2005}, PAGES = {255--274}, } @INPROCEEDINGS{Baumgartner:Mediratta:ASPPlanningBidirectional:KBCS:2004, AUTHOR = {Baumgartner, Peter and Mediratta, Anupam}, EDITOR = {Sasikumar, M. and Vakil, R. and Kavitha, M.}, TITLE = {Improving Stable Models Based Planning by Bidirectional Search}, BOOKTITLE = {Proceedings of the 5th International Conference on Knowledge Based Computer Systems (KBCS 2004)}, PADDRESS = {New Delhi}, ADDRESS = {Hyderabad, India}, PUBLISHER = {ALLIED}, MONTH = {December}, ISBN = {81-7764-711-3}, YEAR = {2004}, PAGES = {404--413}, } @INPROCEEDINGS{Baumgartner:Tinelli:ModelEvolutionCalculusEquality:CADE:2005, AUTHOR = {Baumgartner, Peter and Tinelli, Cesare}, EDITOR = {Nieuwenhuis, Robert}, TITLE = {The Model Evolution Calculus with Equality}, BOOKTITLE = {Automated deduction - CADE-20 : 20th International Conference on Automated Deduction}, PADDRESS = {New York, USA}, ADDRESS = {Tallinn, Estonia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {3632}, ISBN = {3-540-28005-7}, YEAR = {2005}, PAGES = {392--408}, ABSTRACT = {In many theorem proving applications, a proper treatment of equational theories or equality is mandatory. In this paper we show how to integrate a modern treatment of equality in the Model Evolution calculus (ME), a first-order version of the propositional DPLL procedure. The new calculus, MEE, is a proper extension of the ME calculus without equality. Like ME it maintains an explicit ``candidate model'', which is searched for by DPLL-style splitting. For equational reasoning MEE uses an adapted version of the ordered paramodulation inference rule, where equations used for paramodulation are drawn (only) from the candidate model. The calculus also features a generic, semantically justified simplification rule which covers many simplification techniques known from superposition-style theorem proving. Our main result is the refutational completeness of the MEE calculus.}, } @INPROCEEDINGS{BaWe2000a, AUTHOR = {Backes, Werner and Wetzel, Susanne}, EDITOR = {Bosma, Wieb}, TITLE = {New Results on Lattice Basis Reduction in Practice}, BOOKTITLE = {Proceedings of the 4th International Algorithmic Number Theory Symposium (ANTS-IV)}, PADDRESS = {New York, USA}, ADDRESS = {Leiden, Netherlands}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1838}, YEAR = {2000}, PAGES = {135--152}, } @INPROCEEDINGS{BaWe2000b, AUTHOR = {Backes, Werner and Wetzel, Susanne}, EDITOR = {N{\"a}her, Stefan and Wagner, Dorothea}, TITLE = {Lattice Basis Reduction with Dynamic Approximation}, BOOKTITLE = {Proceedings of the 4th Workshop On Algorithm Engineering (WAE-2000)}, PADDRESS = {Saarbr{\"u}cken, Germany}, ADDRESS = {Saarbr{\"u}cken, Deutschland}, PUBLISHER = {Max-Planck-Institut f{\"u}r Informatik}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1982}, YEAR = {2001}, PAGES = {63--73}, } @ARTICLE{BE2001, AUTHOR = {Bockmayr, Alexander and Eisenbrand, Friedrich}, JOURNAL = {Mathematics of Operations Research}, TITLE = {Cutting planes and the elementary closure in fixed dimension}, NUMBER = {2}, MONTH = {May}, VOLUME = {26}, YEAR = {2001}, PAGES = {304--312}, } @ARTICLE{BE98, AUTHOR = {Buchmann, Johannes and Eisenbrand, Friedrich}, JOURNAL = {Mathematics of Computation}, TITLE = {On Factor Refinement in Number Fields}, NUMBER = {225}, PUBLISHER = {AMS}, MONTH = {January}, VOLUME = {68}, YEAR = {1999}, PAGES = {345--350}, } @MASTERSTHESIS{Becker94, AUTHOR = {Becker, Joachim}, TITLE = {{Effiziente Subsumption in Deduktionssystemen}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {May}, YEAR = {1994}, ABSTRACT = {Es wurden Datenstrukturen und Algorithmen in der Programmiersprache C entwickelt, die einen effizienten Subsumptionstest auf Klauseln f{\"u}r einen Resolutionsbeweiser erm{\"o}glichen. Die ben{\"o}tigten Datenstrukturen, mit deren Hilfe man den Subsumptionstest von Term- auf Klauselebene liften kann, wurden in einer "Black-Box" zum Aufbewahren von Klauseln zusammengefa{\ss}t.}, } @ARTICLE{BEHS98, AUTHOR = {Bockmayr, Alexander and Eisenbrand, Friedrich and Hartmann, Mark and Schulz, Andreas S.}, JOURNAL = {Discrete Applied Mathematics}, TITLE = {On the {Chv{\'a}tal} Rank of Polytopes in the 0/1 Cube}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {1/2}, PUBLISHER = {Elsevier}, VOLUME = {98}, YEAR = {1999}, PAGES = {21--27}, } @ARTICLE{BenAmramLee2007, AUTHOR = {Ben-Amram, Amir M. and Lee, Chin Soon}, JOURNAL = {ACM Transactions on Programming Languages and Systems}, TITLE = {Program termination analysis in polynomial time}, ADDRESS = {New York, NY, USA}, NUMBER = {1}, PUBLISHER = {ACM}, MONTH = {January}, VOLUME = {29}, ISBN = {0164-0925}, DOI = {10.1145/1180475.1180480}, YEAR = {2007}, PAGES = {5:1--37}, ABSTRACT = {In an earlier work with Neil D.~Jones, we proposed the ``size-change principle'' for program termination: An infinite computation is \emph{impossible}, if it would imply that some data decrease in size infinitely. Such a property can be deduced from program analysis information in the form of \emph{size-change graphs}. A set of size-change graphs with the desired property is said to satisfy \emph{size-change termination} (SCT). There are many examples of practical programs whose termination can be verified by creating size-change graphs and testing them for SCT. While SCT is decidable, it has high worst-case complexity (complete for \sctext{pspace}). In this paper, we formulate an efficient approach to verify practical instances of SCT. Our procedure has worst-case complexity cubic in the input size. Its effectiveness is demonstrated empirically using a test-suite of over 90 programs.}, } @INCOLLECTION{Bertling-et-al-93, AUTHOR = {Bertling, Hubert and Ganzinger, Harald and Sch{\"a}fers, Renate and Nieuwenhuis, Robert and Orejas, Fernando}, EDITOR = {Hoffmann, Berthold and Krieg-Br{\"u}ckner, Bernd}, TITLE = {Completion Subsystem}, BOOKTITLE = {Program Development by Specification and Transformation, The PROSPECTRA Methodology, Language Family, and System}, CHAPTER = {4.3: {Part III: The System, Chapter}}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {680}, ISBN = {3-540-56733-X}, YEAR = {1993}, PAGES = {460--494}, ABSTRACT = {The paper describes the Knuth/Bendix-like completion subsystem of the PROSPECTRA programming environment. It consists of two independent completion procedures for conditional equations. The paper introduces some of the underlying theory and contains examples that illustrate the use of these procedures.}, } @ARTICLE{BlanchetPodelski2005, AUTHOR = {Blanchet, Bruno and Podelski, Andreas}, JOURNAL = {Theoretical Computer Science}, TITLE = {Verification of Cryptographic Protocols: Tagging Enforces Termination}, ADDRESS = {Amsterdam, The Netherlands}, NUMBER = {1-2}, PUBLISHER = {Elsevier}, MONTH = {March}, VOLUME = {333}, ISBN = {0304-3975}, YEAR = {2005}, PAGES = {67--90}, ABSTRACT = {We investigate a resolution-based verification method for secrecy and authentication properties of cryptographic protocols. In experiments, we could enforce its termination by tagging, a syntactic transformation of messages that leaves attack-free executions invariant. In this paper, we generalize the experimental evidence: we prove that the verification method always terminates for tagged protocols. }, } @INPROCEEDINGS{Bockmayr92a, AUTHOR = {Bockmayr, Alexander}, EDITOR = {Schulz, K. U.}, TITLE = {Algebraic and Logical Aspects of Unification}, BOOKTITLE = {Proc.~1st Workshop on Word Equations and Related Topics}, PADDRESS = {Berlin, Germany}, ADDRESS = {T{\"u}bingen, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {572}, YEAR = {1992}, PAGES = {171--180}, ABSTRACT = {During the last years unification theory has become an important subfield of automated reasoning and logic programming. The aim of the present paper is to relate unification theory to classical work on equation solving in algebra and mathematical logic. We show that many problems in unification theory have their counterpart in classical mathematics and illustrate by various examples how classical results can be used to answer unification-theoretic questions.}, } @INPROCEEDINGS{Bockmayr92b, AUTHOR = {Bockmayr, Alexander}, EDITOR = {Schulz, K. U.}, TITLE = {Model-Theoretic Aspects of Unification}, BOOKTITLE = {Proceedings of the 1st Workshop on Word Equations and Related Topics}, PADDRESS = {Berlin, Germany}, ADDRESS = {T{\"u}bingen, Germany}, PUBLISHER = {Springer}, MONTH = {October}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {572}, YEAR = {1992}, PAGES = {181--196}, ABSTRACT = {Unification is a fundamental operation in various areas of computer science, in particular in automated theorem proving and logic programming. In this paper we establish a relation between unification theory and classical model theory. We show how model-theoretic methods can be used to investigate a generalized form of unification, namely the problem whether, given an equational theory $E$ and a system of equations $S$, there is an extension of the free algebra in $E$ in which $S$ is solvable.}, } @INPROCEEDINGS{Bockmayr92c, AUTHOR = {Bockmayr, Alexander}, EDITOR = {Tchuente, M.}, TITLE = {A Theoretical Basis for Constraint Logic and Functional Programming}, BOOKTITLE = {Proc.~1st African Conference on Research in Computer Science}, PADDRESS = {Rocquencourt, France}, ADDRESS = {Yaound{\'e}, Cameroun}, PUBLISHER = {INRIA}, VOLUME = {2}, YEAR = {1992}, PAGES = {793--804}, } @INPROCEEDINGS{Bockmayr93a, AUTHOR = {Bockmayr, Alexander}, EDITOR = {Karmann, A. and Mosler, K. and Schader, M. and Uebe, G.}, TITLE = {Embedding {OR} Techniques in Constraint Logic Programming}, BOOKTITLE = {Operations Research '92. 17th Symposium on Operations Research}, PADDRESS = {Heidelberg, Germany}, ADDRESS = {Hamburg, Germany}, PUBLISHER = {Physica-Verlag}, YEAR = {1993}, PAGES = {252--254}, } @INPROCEEDINGS{Bockmayr93b, AUTHOR = {Bockmayr, Alexander}, EDITOR = {Benhamou, F. and Colmerauer, A.}, TITLE = {Logic Programming with Pseudo-Boolean Constraints}, BOOKTITLE = {Constraint Logic Programming---Selected Research}, PADDRESS = {Cambridge, USA}, ADDRESS = {?}, PUBLISHER = {MIT Press}, YEAR = {1993}, PAGES = {327--350}, NOTE = {Also available as Research Report MPI-I-91-227}, ABSTRACT = {Boolean constraints play an important role in various constraint logic programming languages. In this paper we consider pseudo-Boolean constraints, that is equations and inequalities between pseudo-Boolean functions. A pseudo-Boolean function is an integer-valued function of Boolean variables and thus a generalization of a Boolean function. Pseudo-Boolean functions occur in many application areas, in particular in problems from operations research. An interesting connection to logic is that inference problems in propositional logic can be translated into linear pseudo-Boolean optimization problems. More generally, pseudo-Boolean constraints can be seen as a particular way of combining two of the most important domains in constraint logic programming: arithmetic and Boolean algebra. In this paper we define a new constraint logic programming language CLP(${\cal PB}$) for logic progamming with pseudo-Boolean constraints. The language is an instance of the general constraint logic programming language scheme CLP(${\cal X}$) and inherits all the typical semantic properties. We show that any pseudo-Boolean constraint has a most general solution and give variable elimination algorithms for pseudo-Boolean unification and unconstrained pseudo-Boolean optimization. Both algorithms subsume the well-known Boolean unification algorithm of B{\"u}ttner and Simonis.}, } @ARTICLE{Bockmayr93c, AUTHOR = {Bockmayr, Alexander}, JOURNAL = {Applicable Algebra in Engineering, Communication and Computing}, TITLE = {Conditional Narrowing Modulo a Set of Equations}, NUMBER = {3}, MONTH = {September}, VOLUME = {4}, YEAR = {1993}, PAGES = {147--168}, ABSTRACT = {Narrowing is a universal unification procedure for equational theories given by a canonical term rewrite system. In this paper we introduce conditional narrowing modulo a set of conditional equations and give a full proof of its correctness and completeness for equational conditional rewrite systems $R,E$ without extravariables where $E$ is regular and $R,E$ is Church-Rosser modulo $E$ and decrasing modulo $E$. This result can be seen as the theoretical foundation of a special form of constraint logic and functional programming.}, } @INPROCEEDINGS{Bockmayr93d, AUTHOR = {Bockmayr, Alexander}, EDITOR = {Bachem, A. and et al.}, TITLE = {Using Strong Cutting Planes in Constraint Logic Programming (Extended Abstract)}, BOOKTITLE = {Operations Research '93, 18th Symposium on Operations Research}, PADDRESS = {Heidelberg, Germany}, ADDRESS = {K{\"o}ln}, PUBLISHER = {Physica-Verlag}, MONTH = {September}, YEAR = {1994}, PAGES = {47--49}, } @INPROCEEDINGS{Bockmayr93h, AUTHOR = {Bockmayr, Alexander}, EDITOR = {Benhamou, F. and Colmerauer, A. and Smolka, G.}, TITLE = {0-1 Constraints and 0-1 Optimization}, BOOKTITLE = {3rd Workshop on Constraint Logic Programming (WCLP '93)}, PADDRESS = {Marseille, France}, ADDRESS = {Marseille, France}, PUBLISHER = {Faculty of Luminy}, YEAR = {1993}, } @INPROCEEDINGS{Bockmayr94c, AUTHOR = {Bockmayr, Alexander}, TITLE = {Cutting planes in constraint logic programming ({A}bstract)}, BOOKTITLE = {Proceedings of the 3rd International Symposium Artificial Intelligence and Mathematics}, PADDRESS = {Boca Raton}, ADDRESS = {Ft. Lauderdale, Florida}, PUBLISHER = {Florida Atlantic University}, YEAR = {1994}, ABSTRACT = {Full version available as Research Report MPI-I-94-207, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken}, } @INPROCEEDINGS{Bockmayr95a, AUTHOR = {Bockmayr, Alexander}, EDITOR = {Podelski, Andreas}, TITLE = {Solving pseudo-Boolean constraints}, BOOKTITLE = {Constraint Programming: Basics and Trends}, TYPE = {Selected Papers}, PADDRESS = {Berlin, Germany}, ADDRESS = {Châtillon-sur-Seine}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {910}, ISBN = {3-540-59155-9}, YEAR = {1995}, PAGES = {22--38}, ABSTRACT = {Pseudo-Boolean constraints are equations or inequalities between integer polynomials in 0-1 variables. On the one hand, they generalize Boolean constraints, on the other hand, they are a restricted form of finite domain constraints. In this paper, we present special constraint solving techniques for the domain {0,1} originating from mathematical programming. The key concepts are the generation of strong valid inequalities for the solution set of a constraint system and the notion of branch-and-cut.}, } @INPROCEEDINGS{Bockmayr96a, AUTHOR = {Bockmayr, Alexander}, EDITOR = {Hanus, Michael and Lloyd, John W. and Moreno Navarro, Juan Jos{\'e}}, TITLE = {Constraints in functional logic programming (Abstract)}, BOOKTITLE = {Integration of functional and logic languages}, TYPE = {Abstract}, PADDRESS = {Wadern, Germany}, ADDRESS = {Schloss Dagstuhl, Germany}, PUBLISHER = {IBFI}, SERIES = {Dagstuhl-Seminar-Report}, VOLUME = {146}, YEAR = {1996}, PAGES = {4}, } @INPROCEEDINGS{BockmayrBarthKasper96, AUTHOR = {Bockmayr, Alexander and Barth, Peter and Kasper, Thomas}, EDITOR = {Steinbach, B.}, TITLE = {Methods and Tools for Pseudo-Boolean Problems}, BOOKTITLE = {2. Workshop Boolesche Probleme}, PADDRESS = {Freiberg, Sachsen}, ADDRESS = {Freiberg, Sachsen}, PUBLISHER = {TU Bergakademie Freiberg, Institut f{\"u}r Informatik}, YEAR = {1996}, PAGES = {105--109}, ABSTRACT = {Pseudo-Boolean problems are a generalization of Boolean problems and combine Boolean algebra with arithmetic. A pseudo-Boolean problem is defined by equations and inequalities between integer polynomials in 0-1 variables. We describe methods and tools for solving pseudo-Boolean problems that combine techniques from automated deduction and operations research. The basic idea is to compute strong valid inequalities for the underlying set of 0-1 vectors.}, } @ARTICLE{BockmayrBrzoskaDeussenVarsek91a, AUTHOR = {Bockmayr, Alexander and Brzoska, C. and Deussen, P. and Varsek, I.}, JOURNAL = {Informatik--Forschung und Entwicklung}, TITLE = {{KA-Prolog: Erweiterungen einer logischen Programmiersprache und ihre effiziente Implementierung}}, VOLUME = {6}, YEAR = {1991}, PAGES = {128--140}, ABSTRACT = {Logic programming is one of the main paradigms in the area of declarative programming. Often it is identified with the programming language Prolog. In this paper we discuss a number of extensions of Prolog that have been investigated in the Sonderforschungsbereich 314 ``Artificial Intelligence - Knowledge-Based Systems'' at the University of Karlsruhe. On the level of unification we extend Prolog's syntactical unification to order-sorted and Boolean unification, on the level of resolution we generalize Prolog's Horn clauses and SLD-Resolution to conditional equations and conditional narrowing. In addition to language extensions themselves we present also methods and tools for their efficient implementation.}, } @INPROCEEDINGS{BockmayrDimopoulos98, AUTHOR = {Bockmayr, Alexander and Dimopoulos, Yannis}, EDITOR = {Frank, Jeremy and Sabin, Mihaela}, TITLE = {Mixed Integer Programming Models for Planning Problems}, BOOKTITLE = {Proceedings of the Workshop on Constraint Problem Reformulation (CP-98)}, PADDRESS = {Moffett Field, USA}, ADDRESS = {Pisa, Italy}, PUBLISHER = {NASA Ames Research Center}, YEAR = {1998}, PAGES = {1--6}, ABSTRACT = {We present some preliminary work on modeling AI planning as a Mixed Integer Programming (MIP) problem. We discuss the main advantages and disadvantages of the approach and compare it to traditional planning frameworks. We investigate a number of MIP models of specific problems, each of them exploiting different strengths of the MIP formulation, and present our computational experience with these models. }, } @INPROCEEDINGS{BockmayrEisenbrand2000, AUTHOR = {Eisenbrand, Friedrich and Bockmayr, Alexander}, EDITOR = {Kirchner, H. and Ringeissen, C.}, TITLE = {Combining logic and optimization in cutting plane theory}, BOOKTITLE = {Proceedings of the Workshop on Frontiers of Combining Systems (FROCOS-2000)}, TYPE = {Extended Abstract}, PADDRESS = {Berlin, Germany}, ADDRESS = {Nancy, France}, PUBLISHER = {Springer}, MONTH = {March}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1794}, YEAR = {2000}, PAGES = {1--17}, } @INPROCEEDINGS{BockmayrKasper96, AUTHOR = {Bockmayr, Alexander and Kasper, Thomas}, EDITOR = {Geske, Ulrich and Simonis, Helmut}, TITLE = {Pseudo-Boolean and Finite Domain Constraint Programming: A Case Study}, BOOKTITLE = {Deklarative Constraint Programmierung}, ORGANIZATION = {GDM-Forschungszentrum Informationstechnik GmbH}, PADDRESS = {Sankt Augustin, Germany}, ADDRESS = {Dresden, Germany}, NUMBER = {297}, PUBLISHER = {GMD}, MONTH = {September}, SERIES = {GMD-Studien}, ISBN = {3-88457-297-0}, YEAR = {1996}, PAGES = {29--41}, ABSTRACT = {Pseudo-Boolean constraints are a special form of finite domain constraints where all variables are defined over the domain $\{0,1\}$. To solve pseudo-Boolean constraints, specialized constraint solving algorithms have been developed. In this paper, we compare finite domain and pseudo-Boolean constraint techniques on a classical application of finite domain constraint programming, the warehouse location problem. Although the finite domain model is very natural and theoretically has a much smaller search space, the 0-1 model with specialized constraint solving techniques turns out to be more efficient.}, } @ARTICLE{BockmayrKasper98, AUTHOR = {Bockmayr, Alexander and Kasper, Thomas}, JOURNAL = {INFORMS Journal on Computing}, TITLE = {Branch-and-Infer: A Unifying Framework for Integer and Finite Domain Constraint Programming}, NUMBER = {3}, VOLUME = {10}, YEAR = {1998}, PAGES = {287--300}, ABSTRACT = { We introduce branch-and-infer, a unifying framework for integer linear programming and finite domain constraint programming. We use this framework to compare the two approaches with respect to their modeling and solving capabilities, to introduce symbolic constraint abstractions into integer programming, and to discuss possible combinations of the two approaches.}, } @ARTICLE{BockmayrKrischerWerner94, AUTHOR = {Bockmayr, Alexander and Krischer, Stefan and Werner, Andreas}, JOURNAL = {Fundamenta Informaticae}, TITLE = {Narrowing strategies for arbitrary canonical systems}, NUMBER = {1,2}, PUBLISHER = {IOS Press}, MONTH = {September}, VOLUME = {24}, ISBN = {0169-2968}, YEAR = {1995}, PAGES = {125--155}, ABSTRACT = {Narrowing is a universal unification procedure for equational theories defined by a canonical term rewriting system. In its original form it is extremely inefficient. Therefore, many optimizations have been proposed during the last years. In this paper, we present the narrowing strategies for arbitrary canonical systems in a uniform framework and introduce the new narrowing strategy LSE narrowing. LSE narrowing is complete and improves all other strategies which are complete for arbitrary canonical systems. It is optimal in the sense that two different LSE narrowing derivations cannot generate the same narrowing substitution. Moreover, LSE narrowing computes only normalized narrowing substitutions.}, } @INPROCEEDINGS{BockmayrRadermacher93e, AUTHOR = {Bockmayr, Alexander and Radermacher, F. J.}, EDITOR = {Herzog, O. and Christaller, Th. and Sch{\"u}tt, D.}, TITLE = {{K{\"u}nstliche Intelligenz und Operations Research}}, BOOKTITLE = {Grundlagen und Anwendungen der K{\"u}nstlichen Intelligenz. 17. Fachtagung f{\"u}r K{\"u}nstliche Intelligenz}, PADDRESS = {Berlin, Germany}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, SERIES = {Informatik Aktuell}, YEAR = {1993}, PAGES = {249--254}, } @INCOLLECTION{BockmayrWeispfenning01, AUTHOR = {Bockmayr, Alexander and Weispfenning, V.}, EDITOR = {Robinson, Alan and Voronkov, Andrei}, TITLE = {Solving numerical constraints}, BOOKTITLE = {Handbook of Automated Reasoning}, CHAPTER = {12}, ADDRESS = {Amsterdam, the Netherlands}, PUBLISHER = {Elsevier}, MONTH = {January}, VOLUME = {1}, YEAR = {2001}, PAGES = {751--842}, ABSTRACT = {In \cite{BockmayrWeispfenning01}, we give an overview of solving numerical constraints in the context of automated reasoning. Emphasis is on logical aspects of numerical constraints. We view them as atomic formulae in first-order predicate logic that are interpreted over some numerical domain like the real, rational, or integer numbers. We present various inference systems for reasoning with numerical constraints, describe the algebraic and geometric structure of their solution set, and present fundamental algorithms for deciding satisfiability, computing one or all solutions, and deducing new constraints.}, } @INPROCEEDINGS{BockmayrWerner94, AUTHOR = {Bockmayr, Alexander and Werner, Andreas}, EDITOR = {Dershowitz, Nachum and Lindenstrauss, Naomi}, TITLE = {LSE narrowing for decreasing conditional term rewrite systems}, BOOKTITLE = {Conditional Term Rewriting Systems CTRS'94}, TYPE = {Proceedings}, PADDRESS = {Berlin, Germany}, ADDRESS = {Jerusalem, Israel}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {968}, ISBN = {3-540-60381-6}, YEAR = {1995}, PAGES = {51--70}, ABSTRACT = {In an earlier paper, we introduced LSE narrowing, which is an optimal narrowing strategy for arbitrary canonical term rewrite systems without additional properties such as orthogonality or constructor discipline. In this paper, we extend LSE narrowing to confluent and decreasing conditional term rewrite systems.}, } @PHDTHESIS{bockmayr_habil_96, AUTHOR = {Bockmayr, Alexander}, TITLE = {{Gleichheit und Constraints in der Logikprogrammierung}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Habilitation thesis}, MONTH = {June}, YEAR = {1996}, } @ARTICLE{Booth-jancl, AUTHOR = {Booth, Richard}, JOURNAL = {Journal of Applied Non-Classical Logics}, TITLE = {The lexicographic closure as a revision process}, NUMBER = {1/2}, VOLUME = {11}, YEAR = {2001}, PAGES = {35--58}, } @INPROCEEDINGS{Booth2000, AUTHOR = {Booth, Richard}, EDITOR = {Baral, C. and Truszczynski, M.}, TITLE = {The lexicographic closure as a revision process}, BOOKTITLE = {Proceedings of the 8th International Workshop on Non-Monotonic Reasoning (NMR 2000)}, PADDRESS = {?}, ADDRESS = {Breckenridge, Colorado, USA}, PUBLISHER = {?}, YEAR = {2000}, NOTE = {Extended version to appear in "Journal of Applied Non-Classical Logics"}}, ABSTRACT = {The connections between nonmonotonic reasoning and belief revision are well-known. A central problem in the area of nonmonotonic reasoning is the problem of default entailment, i.e., when should an item of default information representing "if A is true then, normally, B is true" be said to follow from a given set of items of such information. Many answers to this question have been proposed but, surprisingly, virtually none have attempted any explicit connection to belief revision. The aim of this paper is to give an example of how such a connection can be made by showing how the lexicographic closure of a set of defaults may be conceptualised as a process of iterated revision by sets of sentences. Specifically we use the revision process of Nayak.}, } @MASTERSTHESIS{BozkurtDiplSiek1995, AUTHOR = {Bozkurt, Ahmet}, TITLE = {Strategien f{\"u}r Resolutionsbeweiser in Logik h{\"o}herer Stufe}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1995}, } @INPROCEEDINGS{BP-Fossacs03, AUTHOR = {Blanchet, Bruno and Podelski, Andreas}, EDITOR = {Gordon, Andrew D.}, TITLE = {Verification of Cryptographic Protocols: Tagging Enforces Termination}, BOOKTITLE = {Foundations of software science and computation structures : 6th International Conference, FOSSACS 2003}, PADDRESS = {Berlin, Germany}, ADDRESS = {Warsaw, Poland}, PUBLISHER = {Springer}, MONTH = {April}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2620}, ISBN = {3-540-00897-7}, YEAR = {2003}, PAGES = {136--152}, } @ARTICLE{BPR-STTT03, AUTHOR = {Podelski, Andreas and Ball, Tom and Rajamani, Sriram K.}, JOURNAL = {International Journal on Software Tools for Technology Transfer (STTT)}, TITLE = {Boolean and {Cartesian} Abstraction for Model Checking {C} Programs}, ADDRESS = {Berlin, Germany}, NUMBER = {3}, PUBLISHER = {Springer}, VOLUME = {5}, ISBN = {1433-2779}, YEAR = {2003}, PAGES = {1--15}, } @INPROCEEDINGS{BPR-Tacas03, AUTHOR = {Podelski, Andreas and Ball, Tom and Rajamani, Sriram K.}, EDITOR = {Kaoen, Joost-Pieter and Stevens, Perdita}, TITLE = {Relative Completeness of Abstraction Refinement for Software Model Checking}, BOOKTITLE = {Tools and algorithms for the construction and analysis of systems : 8th International Conference, TACAS 2002}, PADDRESS = {Berlin, Germany}, ADDRESS = {Grenoble, France}, PUBLISHER = {Springer}, MONTH = {April}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2280}, ISBN = {3-540-43419-4}, YEAR = {2002}, PAGES = {158--172}, } @INPROCEEDINGS{BrafmanHoffmann2004, AUTHOR = {Brafman, Ronen and Hoffmann, J{\"o}rg}, EDITOR = {Zilberstein, Shlomo and Koehler, Jana and Koenig, Sven}, TITLE = {Conformant Planning via Heuristic Forward Search: A New Approach}, BOOKTITLE = {Proceedings of the Fourteenth International Conference on Automated Planning and Scheduling (ICAPS 2004)}, PADDRESS = {Menlo Park, USA}, ADDRESS = {Whistler, Canada}, PUBLISHER = {AAAI}, MONTH = {June}, ISBN = {1-57735-200-9}, YEAR = {2004}, PAGES = {355--364}, } @MASTERSTHESIS{Brahm2013, AUTHOR = {Brahm, Uwe}, TITLE = {{M{\"o}glichkeiten des Groupware-Einsatzes im Umfeld des Wissenschaftlerarbeitsplatzes am Beispiel des Max-Planck-Instituts f{\"u}r Informatik}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {November}, YEAR = {2013}, PAGES = {149}, NOTE = {Abschlussarbeit zur Erlangung des akademischen Grades eines Magister Artium (M. A.) vorgelegt an der Fachrichtung 5.6 - Informationswissenschaft, Fakult{\"a}t 5 - Philosophische Fakult{\"a}t III der Universit{\"a}t des Saarlandes}, } @ARTICLE{BrahmPitz1990, AUTHOR = {Brahm, Uwe and Pitz, Werner}, JOURNAL = {c't Magazin f{\"u}r computer technik}, TITLE = {{Parkw{\"a}chter}}, ADDRESS = {Hannover, Germany}, NUMBER = {3}, PUBLISHER = {Heise}, MONTH = {March}, ISBN = {0724-8679}, YEAR = {1990}, PAGES = {252--253}, } @MISC{BrahmPresentation20060912, AUTHOR = {Brahm, Uwe}, TITLE = {Eine integrierte Publikationsverwaltung am Beispiel des Max-Planck-Instituts f{\"u}r Informatik}, HOWPUBLISHED = {Folien eines Vortrages am 12. September 2006 im Zentrum f{\"u}r Informationsmanagement der Max-Planck-Gesellschaft (ZIM) in Garching bei M{\"u}nchen}, MONTH = {September}, YEAR = {2006}, PAGES = {15}, } @ARTICLE{BrinkBritzSchmidt94, AUTHOR = {Brink, Chris and Britz, Katarina and Schmidt, Renate A.}, JOURNAL = {Formal Aspects of Computing}, TITLE = {Peirce Algebras}, ADDRESS = {Berlin, Germany}, NUMBER = {3}, PUBLISHER = {Springer}, MONTH = {April}, VOLUME = {6}, ISBN = {0934-5043}, YEAR = {1994}, PAGES = {339--358}, NOTE = {Also available as Research Report MPI-I-92-229, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken, Germany (July 1992), and as Research Report RR 140, Department of Mathematics, University of Cape Town, Cape Town, South Africa (August 1992). An extended abstract appears in Nivat, M., Rattray, C., Rus, T. and Scollo, G. (eds), {\em Algebraic Methodology and Software Technology (AMAST'93): Proceedings of the 3rd International Conference on Algebraic Methodology and Software Technology}. {\em Workshops in Computing} Series, Springer-Verlag, London, 165-168 (1994).}, ABSTRACT = {We present a two-sorted algebra, called a {\em Peirce algebra of relations} and sets interacting with each other. In a Peirce algebra, sets can combine with each other as in a Boolean algebra, relations can combine with each other as in a relation algebra, and in addition we have both a set-forming operator on relations (the Peirce product of Boolean modules) and a relation-forming operator on sets (a cylindrification operation). Two applications of Peirce algebras are given. The first points out that Peirce algebras provide a natural algebraic framework for modelling certain programming constructs. The second shows that the so-called {\em terminological logics} arising in knowledge representation have evolved a semantics best described as a calculus of relations interacting with sets.}, } @INPROCEEDINGS{BrinkBritzSchmidt94b, AUTHOR = {Brink, Chris and Britz, Katarina and Schmidt, Renate A.}, EDITOR = {Nivat, Maurice and Rattray, Charles and Rus, Teodor and Scollo, Guiseppe}, TITLE = {Peirce Algebras: Extended Abstract}, BOOKTITLE = {Proceedings of the 3rd International Conference on Algebraic Methodology and Software Technology (AMAST '93)}, PADDRESS = {London, UK}, ADDRESS = {University of Twente, Enschede, Netherlands}, PUBLISHER = {Springer}, SERIES = {Workshops in Computing}, YEAR = {1994}, PAGES = {163--166}, } @MASTERSTHESIS{Brinker2000, AUTHOR = {Brinker, Christof}, TITLE = {{Geometrisches Schlie{\ss}en mit SPASS}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {January}, YEAR = {2000}, } @ARTICLE{BrinkGabbayOhlbach94, AUTHOR = {Brink, Chris and Gabbay, Dov M. and Ohlbach, Hans J{\"u}rgen}, JOURNAL = {Journal of Computers and Mathematics with Applications}, TITLE = {Towards Automating Duality}, NUMBER = {2}, VOLUME = {29}, YEAR = {1994}, PAGES = {73--90}, NOTE = {Special Issue on Automated Reasoning. Also available as Research Report MPI-I-93-220, Saarbr{\"u}cken}, ABSTRACT = {Dualities between different theories occur frequently in mathematics and logic - between syntax and semantics of a logic, between structures and power structures, between relations and relational algebras, to name just a few. In this paper we show for the case of structures and power structures how corresponding properties of the two related structures can be computed fully automatically by means of quantifier elimination algorithms and predicate logic theorem provers. We illustrate the method with a large number of examples and we give enough technical hints to enable the reader who has access to the OTTER theorem prover to experiment herself.}, } @ARTICLE{BrinkRewitzkySchmidt91a, AUTHOR = {Brink, Chris and Rewitzky, I. M. and Schmidt, Renate A.}, JOURNAL = {The Computer Journal}, TITLE = {Autodescriptivity: Beware!}, NUMBER = {4}, VOLUME = {34}, YEAR = {1991}, PAGES = {380--381}, ABSTRACT = {Non-classical logics, and in particular many-valued logics, are increasingly used in the study of formal aspects of computing. For example, a recent paper by P. F. Gibbins in this {\em Journal} presents a 3-valued propositional logic for VDM. In the use of such logics one naturally relies on earlier work done by logicians, a case in point being Gibbin's use of the concept of autodescriptivity, introduced by N. Rescher. The purpose of this Note is to sound a warning that Rescher's exposition of autodescriptivity is seriously flawed, and to clarify the autodescriptivity of the logic of VDM.}, } @INPROCEEDINGS{CantuBundySmaillBasin96, AUTHOR = {Cantu, Francisco and Bundy, Alan and Smaill, Alan and Basin, David A.}, EDITOR = {Srivas, M. and Camilleri, A.}, TITLE = {Experiments in Automating Hardware Verification using Inductive Proof Planning}, BOOKTITLE = {Proceedings of the Formal Methods for Computer-Aided Design Conference (FMCAD'96)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Palo Alto, CA, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1166}, YEAR = {1996}, PAGES = {94--108}, } @INPROCEEDINGS{CDGMT01, AUTHOR = {Charatonik, Witold and Dal Zilio, Silvano and Gordon, Andrew Donald and Mukhopadhyay, Supratik and Talbot, Jean-Marc}, EDITOR = {Honsell, Furio and Miculan, Marino}, TITLE = {The Complexity of Model Checking Mobile Ambients}, BOOKTITLE = {Foundations of Software Science and Computation Structures. Proceedings of the 4th International Conference (FOSSACS-01). Held as Part of the Joint European Conferences on Theory and Practice of Software (ETAPS-01)}, TYPE = {Extended Abstract}, PADDRESS = {Berlin, Germany}, ADDRESS = {Genova, Italy}, PUBLISHER = {Springer}, MONTH = {April}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2030}, ISBN = {3-540-41864-4}, YEAR = {2001}, PAGES = {152--167}, ABSTRACT = {We settle the complexity bounds of the model checking problem for the replication-free ambient calculus with public names against the ambient logic without parallel adjunct. We show that the problem is PSPACE-complete. For the complexity upper-bound, we devise a new representation of processes that remains of polynomial size during process execution; this allows us to keep the model checking procedure in polynomial space. Moreover, we prove PSPACE-hardness of the problem for several quite simple fragments of the calculus and the logic; this suggests that there are no interesting fragments with polynomial-time model checking algorithms.}, } @TECHREPORT{CDGMT2001-techrep, AUTHOR = {Charatonik, Witold and Dal Zilio, Silvano and Gordon, Andrew Donald and Mukhopadhyay, Supratik and Talbot, Jean-Marc}, TITLE = {The Complexity of Model Checking Mobile Ambients}, INSTITUTION = {Microsoft Research, Microsoft Corporation}, TYPE = {Technical Report}, ADDRESS = {Redmond, USA}, NUMBER = {MSR-TR-2001-03}, MONTH = {May}, YEAR = {2001}, PAGES = {50}, ABSTRACT = { We settle the complexity bounds of the model checking problem for the replication-free ambient calculus with public names against the ambient logic without parallel adjunct. We show that the problem is PSPACE-complete. For the complexity upper-bound, we devise a new representation of processes that remains of polynomial size during process execution; this allows us to keep the model checking procedure in polynomial space. Moreover, we prove PSPACE-hardness of the problem for several quite simple fragments of the calculus and the logic; this suggests that there are no interesting fragments with polynomial-time model checking algorithms.}, } @INPROCEEDINGS{Charatonik-ESOP00, AUTHOR = {Charatonik, Witold}, EDITOR = {Smolka, Gert}, TITLE = {Directional Type Checking for Logic Programs: {Beyond} Discriminative Types}, BOOKTITLE = {Proceedings of the 8th European Symposium on Programming (ESOP-00)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, MONTH = {March}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1782}, ISBN = {3-540-67262-1}, YEAR = {2000}, PAGES = {72--87}, ABSTRACT = { Directional types form a type system for logic programs which is based on the view of a predicate as a {\em directional procedure\/} which, when applied to a tuple of input terms, generates a tuple of output terms. It is known that directional-type checking wrt.\ arbitrary types is undecidable; several authors proved decidability of the problem wrt.\ discriminative regular types. In this paper, using techniques based on tree automata, we show that directional-type checking for logic programs wrt.\ general regular types is \dexptime-complete and fixed-parameter linear. The letter result shows that despite the exponential lower bound, the type system might be usable in practice.}, } @ARTICLE{Charatonik-IPL98, AUTHOR = {Charatonik, Witold}, JOURNAL = {Information Processing Letters}, TITLE = {An Undecidable Fragment of the Theory of Set Constraints}, ADDRESS = {Amsterdam, the Netherlands}, PUBLISHER = {Elsevier}, MONTH = {November}, VOLUME = {68}, ISBN = {0020-0190}, YEAR = {1998}, PAGES = {147--151}, ABSTRACT = {Set constraints are inclusions between expressions denoting sets of trees. In atomic set constraints, the syntax of set expressions is restricted not to contain any Boolean set operators. Using a reduction from the Hilbert's Tenth Problem we prove the undecidability of the $\exists^*\forall^*$-fragment of the first-order theory of atomic set constraints. This improves recent results by Seynhaeve et.\ al.}, } @PHDTHESIS{Charatonik2002habil, AUTHOR = {Charatonik, Witold}, TITLE = {{Direktionale Typen in der Logischen Programmierung}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Habilitation thesis}, YEAR = {2002}, ABSTRACT = { Abstract der Antrittsvorlesung: In Typsystemen f{\"u}r logische Programme wurden Pr{\"a}dikate bisher als ungerichtete Relationen betrachtet. Dies entspricht nicht der Praxis des Programmierens. In dem Vortrag werde ich das System der direktionalen Typen vorstellen, das Pr{\"a}dikate als Prozeduren betrachtet und die Zusammenh{\"a}nge zwischen Eingabe- und Ausgabewerten beschreibt. Insbesondere werde ich {\"u}ber Typinferenz und Typpr{\"u}fen und die Komplexit{\"a}t dieser Probleme sprechen.}, } @ARTICLE{Charatonik98, AUTHOR = {Charatonik, Witold}, JOURNAL = {Information and Computation}, TITLE = {Set Constraints in Some Equational Theories}, PUBLISHER = {Academic Press}, VOLUME = {142}, ISBN = {0890-5401}, YEAR = {1998}, PAGES = {40--75}, } @ARTICLE{CharatonikDGMT2003, AUTHOR = {Charatonik, Witold and Dal Zilio, Silvano and Gordon, Andrew Donald and Mukhopadhyay, Supratik and Talbot, Jean-Marc}, JOURNAL = {Theoretical Computer Science}, TITLE = {Model checking mobile ambients}, ADDRESS = {Amsterdam, The Netherlands}, NUMBER = {1-3}, PUBLISHER = {Elsevier}, MONTH = {November}, VOLUME = {308}, ISBN = {0304-3975}, YEAR = {2003}, PAGES = {277--331}, ABSTRACT = {We settle the complexity bounds of the model checking problem for the ambient calculus with public names against the ambient logic. We show that if either the calculus contains replication or the logic contains the guarantee operator, the problem is undecidable. In the case of the replication-free calculus and guarantee-free logic we prove that the problem is PSPACE-complete. For the complexity upper-bound, we devise a new representation of processes that remains of polynomial size during process execution; this allows us to keep the model checking procedure in polynomial space. Moreover, we prove PSPACE-hardness of the problem for several quite simple fragments of the calculus and the logic; this suggests that there are no interesting fragments with polynomial-time model checking algorithms. }, } @INPROCEEDINGS{CharatonikGeorgievaMaier2005, AUTHOR = {Charatonik, Witold and Georgieva, Lilia and Maier, Patrick}, EDITOR = {Ong, Luke}, TITLE = {Bounded Model Checking of Pointer Programs}, BOOKTITLE = {Computer Science Logic; 19th International Workshop, CSL 2005; 14th Annual Conference of the EACSL}, ORGANIZATION = {European Association for Computer Science Logic (EACSL)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Oxford, UK}, PUBLISHER = {Springer}, MONTH = {August}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3634}, ISBN = {3-540-28231-9}, YEAR = {2005}, PAGES = {397--412}, ABSTRACT = {We propose a bounded model checking procedure for programs manipulating dynamically allocated pointer structures. Our procedure checks whether a program execution of length n ends in an error (e.g., a NULL dereference) by testing if the weakest precondition of the error condition together with the initial condition of the program (e.g., program variable x points to a circular list) is satisfiable. We express error conditions as formulas in the 2-variable fragment of the Bernays-Schoenfinkel class with equality. We show that this fragment is closed under computing weakest preconditions. We express the initial conditions by unary relations which are defined by monadic Datalog programs. Our main contribution is a small model theorem for the 2-variable fragment of the Bernays-Schoenfinkel class extended with least fixed points expressible by certain monadic Datalog programs. The decidability of this extension of first-order logic gives us a bounded model checking procedure for programs manipulating dynamically allocated pointer structures. In contrast to SAT-based bounded model checking, we do not bound the size of the heap a priori, but allow for pointer structures of arbitrary size. Thus, we are doing bounded model checking of infinite state transition systems.}, } @INPROCEEDINGS{CharatonikGT2002, AUTHOR = {Charatonik, Witold and Gordon, Andrew Donald and Talbot, Jean-Marc}, EDITOR = {Le M{\'e}tayer, Daniel}, TITLE = {Finite-Control Mobile Ambients}, BOOKTITLE = {Programming languages and systems: 11th European Symposium on Programming, ESOP 2002. Held as Part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2002}, PADDRESS = {Berlin, Germany}, ADDRESS = {Grenoble, France}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2305}, ISBN = {3-540-43363-5}, YEAR = {2002}, PAGES = {295--313}, ABSTRACT = {We define a finite-control fragment of the ambient calculus, a formalism for describing distributed and mobile computations. A series of examples demonstrates the expressiveness of our fragment. In particular, we encode the choice-free, finite-control, synchronous $\pi$-calculus. We present an algorithm for model checking this fragment against the ambient logic (without composition adjunct). This is the first proposal of a model checking algorithm for ambients to deal with recursively-defined, possibly nonterminating, processes. Moreover, we show that the problem is PSPACE-complete, like other fragments considered in the literature. Finite-control versions of other process calculi are obtained via various syntactic restrictions. Instead, we rely on a novel type system that bounds the number of active ambients and outputs in a process; any typable process has only a finite number of derivatives.}, } @INPROCEEDINGS{CharatonikMNPW-LICS98, AUTHOR = {Charatonik, Witold and McAllester, David and Niwinski, Damian and Podelski, Andreas and Walukiewicz, Igor}, EDITOR = {Pratt, Vaughan}, TITLE = {The {H}orn Mu-calculus}, BOOKTITLE = {Proceedings of the 13th Annual IEEE Symposium on Logic in Computer Science (LICS-98)}, ORGANIZATION = {IEEE Technical Committee on Mathematical Foundations of Computing}, TYPE = {Extended Abstract}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Indianapolis, Indiana}, PUBLISHER = {IEEE}, MONTH = {June}, ISBN = {0-8186-8506-9}, YEAR = {1998}, PAGES = {58--69}, ABSTRACT = { The Horn $\mu$-calculus is a logic programming language allowing arbitrary nesting of least and greatest fixed points. The Horn $\mu$-programs can naturally expresses safety and liveness properties for reactive systems. We extend the set-based analysis of classical logic programs by mapping arbitrary $\mu$-programs into ``uniform'' $\mu$-programs. Our two main results are that uniform $\mu$-programs express regular sets of trees and that emptiness for uniform $\mu$-programs is EXPTIME-complete. Hence we have a nontrivial decidable relaxation for the Horn $\mu$-calculus. In a different reading, the results express a kind of robustness of the notion of regularity: alternating Rabin tree automata preserve the same expressiveness and algorithmic complexity if we extend them with pushdown transition rules (in the same way B\"uchi extended word automata to canonical systems).}, } @INPROCEEDINGS{CharatonikMP2002, AUTHOR = {Charatonik, Witold and Mukhopadhyay, Supratik and Podelski, Andreas}, EDITOR = {Cortesi, Agostino}, TITLE = {Compositional Termination Analysis of Symbolic Forward Analysis}, BOOKTITLE = {Verification, Model Checking, and Abstract Interpretation. Third International Workshop, VMCAI 2002}, PADDRESS = {Berlin, Germany}, ADDRESS = {Venice, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2294}, ISBN = {3-540-43631-6}, YEAR = {2002}, PAGES = {109--125}, ABSTRACT = {Existing model checking tools for infinite state systems, such as UPPAAL, HYTECH and KRONOS, use symbolic forward analysis, a possibly nonterminating procedure. We give termination criteria that allow us to reason compositionally about systems defined with asynchronous parallel composition; we can prove the termination of symbolic forward analysis for a composed system from the syntactic conditions satisfied by the component systems. Our results apply to nonlinear hybrid systems; in particular to rectangular hybrid systems, timed automata and o-minimal systems. In the case of integer-valued systems we give negative results: forward analysis is not well-suited for this class of inite-state systems.}, } @INPROCEEDINGS{CharatonikMP2002a, AUTHOR = {Charatonik, Witold and Mukhopadhyay, Supratik and Podelski, Andreas}, EDITOR = {Stuckey, Peter J.}, TITLE = {Constraint-Based Infinite Model Checking and Tabulation for Stratified CLP}, BOOKTITLE = {Logic Programming. 18th International Conference, ICLP 2002}, PADDRESS = {Berlin, Germany}, ADDRESS = {Copenhagen, Denmark}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2401}, ISBN = {3-540-43930-7}, YEAR = {2002}, PAGES = {115--129}, ABSTRACT = {Forward analysis procedures for infinite-state systems such as timed systems were limited to safety properties. We give the first constraint-based forward analysis for infinite-state systems that goes beyond safety properties. Namely, we take the restriction of the $\mu$-calculus to least-fixpoint formulas where negation is applied to closed subformulas only. We characterize these properties as perfect models of constraint logic programs, and we present a tabulation procedure for the top-down evaluation of stratified constraint logic programs.}, } @INPROCEEDINGS{CharatonikPodelski-cp96, AUTHOR = {Charatonik, Witold and Podelski, Andreas}, EDITOR = {Freuder, Eugene}, TITLE = {The Independence Property of a Class of Set Constraints}, BOOKTITLE = {Principles and Practice of Constraint Programming, Proceedings of the Second International Conference (CP'96)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Cambridge, USA}, PUBLISHER = {Springer}, MONTH = {August}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1118}, ISBN = {3-540-61551-2}, YEAR = {1996}, PAGES = {76--90}, ABSTRACT = {We investigate a class of set constraints that is used for the type analysis of concurrent constraint programs. Its constraints are inclusions between first-order terms (without set operators) interpreted over non-empty sets of trees. We show that this class has the independence property. We also give a polynomial algorithm for entailment. The independence property is a fundamental property of constraint systems. It says that the constraints cannot express disjunctions, or, equivalently, that negated conjuncts are independent from each other. Its direct algorithmic consequence is that testing the satisfiability of constraints with negated conjuncts can be reduced to entailment. }, } @INPROCEEDINGS{CharatonikPodelski-RTA98, AUTHOR = {Charatonik, Witold and Podelski, Andreas}, EDITOR = {Nipkow, Tobias}, TITLE = {Co-definite Set Constraints}, BOOKTITLE = {Proceedings of the 9th International Conference on Rewriting Techniques and Applications (RTA-98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Tsukuba, Japan}, PUBLISHER = {Springer}, MONTH = {March}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1379}, ISBN = {3-540-64301-X}, YEAR = {1998}, PAGES = {211--225}, ABSTRACT = { In this paper, we introduce the class of co-definite set constraints. This is a natural subclass of set constraints which, when satisfiable, have a {\em greatest}\/ solution. It is practically motivated by the set-based analysis of logic programs with the greatest-model semantics. We present an algorithm solving co-definite set constraints and show that their satisfiability problem is DEXPTIME-complete.}, } @INPROCEEDINGS{CharatonikPodelski-SAS98, AUTHOR = {Charatonik, Witold and Podelski, Andreas}, EDITOR = {Levi, Giorgio}, TITLE = {Directional Type Inference for Logic Programs}, BOOKTITLE = {Proceedings of the 5th International Symposium in Static Analysis (SAS-98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Pisa, Italy}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1503}, ISBN = {3-540-65014-8}, YEAR = {1998}, PAGES = {278--294}, ABSTRACT = { We follow the set-based approach to directional types proposed by Aiken and Lakshman$\:$\cite{AikenL:sas94}. Their type \emph{checking} algorithm works via set constraint solving and is sound and complete for given discriminative types. We characterize directional types in model-theoretic terms. We present an algorithm for \emph{inferring} directional types. The directional type that we derive from a logic program~$\P$ is uniformly at least as precise as any discriminative directional type of~$\P$, i.e., any directional type out of the class for which the type {\em checking\/} algorithm of Aiken and Lakshman is sound and complete. We improve their algorithm as well as their lower bound and thereby settle the complexity (D{\footnotesize EXPTIME}-complete) of the corresponding problem.}, } @INPROCEEDINGS{CharatonikPodelski-tacas98, AUTHOR = {Charatonik, Witold and Podelski, Andreas}, EDITOR = {Steffen, Bernhardt}, TITLE = {Set-Based Analysis of Reactive Infinite-state Systems}, BOOKTITLE = {Tools and Algorithms for the Construction and Analysis of Systems (TACAS-98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Lisbon, Portugal}, PUBLISHER = {Springer}, MONTH = {March}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1384}, ISBN = {3-540-64356-7}, YEAR = {1998}, PAGES = {358--375}, ABSTRACT = { We present an automated abstract verification method for infinite-state systems specified by logic programs (which are a uniform and intermediate layer to which diverse formalisms such as transition systems, pushdown processes and while programs can be mapped). \linebreak We establish connections between: logic program semantics and CTL properties, set-based program analysis and pushdown processes, and also between model checking and constraint solving, viz.\ theorem proving. \linebreak We show that set-based analysis can be used to compute supersets of the values of program variables in the states that satisfy a given CTL property.}, } @INPROCEEDINGS{CharatonikPodelskiLICS97, AUTHOR = {Charatonik, Witold and Podelski, Andreas}, EDITOR = {Winskel, Glynn}, TITLE = {Set Constraints with Intersection}, BOOKTITLE = {Proceedings of the Twelfth Annual IEEE Symposium on Logic in Computer Science (LICS-97)}, ORGANIZATION = {IEEE Computer Society}, PADDRESS = {New York, USA}, ADDRESS = {Warsaw, Poland}, PUBLISHER = {IEEE}, YEAR = {1997}, PAGES = {362--372}, } @INPROCEEDINGS{CharatonikPodelskiTalbot-POPL00, AUTHOR = {Charatonik, Witold and Podelski, Andreas and Talbot, Jean-Marc}, TITLE = {Paths vs. Trees in Set-based Program Analysis}, BOOKTITLE = {Proceedings of the 27th ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages (POPL-00)}, PADDRESS = {New York, USA}, ADDRESS = {Boston, Massachusetts, USA}, PUBLISHER = {ACM}, MONTH = {January}, ISBN = {1-58113-125-9}, YEAR = {2000}, PAGES = {330--337}, ABSTRACT = { Set-based analysis of logic programs provides an accurate method for descriptive type-checking of logic programs. The key idea of this method is to upper approximate the least model of the program by a regular set of trees. In 1991, Fr\"uhwirth, Shapiro, Vardi and Yardeni raised the question whether it can be more efficient to use the domain of sets of paths instead, {\em i.e.}, to approximate the least model by a regular set of words. We answer the question negatively by showing that type-checking for path-based analysis is as hard as the set-based one, that is DEXPTIME-complete. This result has consequences also in the areas of set constraints, automata theory and model checking.}, } @INPROCEEDINGS{CharatonikTalbot-csl01, AUTHOR = {Charatonik, Witold and Talbot, Jean-Marc}, EDITOR = {Fribourg, Laurent}, TITLE = {The Decidability of Model Checking Mobile Ambients}, BOOKTITLE = {Computer science logic (CSL-01) : 15th International Workshop, CSL 2001, Annual Conference of the EACSL}, ORGANIZATION = {European Association for Computer Science Logic (EACSL)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Paris, France}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2142}, ISBN = {3-540-42554-3}, YEAR = {2001}, PAGES = {339--354}, ABSTRACT = { The ambient calculus is a formalism for describing the mobility of both software and hardware. The ambient logic is a modal logic designed to specify properties of distributed and mobile computations programmed in the ambient calculus. In this paper we investigate the border between decidable and undecidable cases of model checking mobile ambients for some fragments of the ambient calculus and the ambient logic. Recently, Cardelli and Gordon presented a model-checking algorithm for a fragment of the calculus (without name restriction and without replication) against a fragment of the logic (without composition adjunct) and asked the question, whether this algorithm could be extended to include either replication in the calculus or composition adjunct in the logic. Here we answer this question negatively: it is not possible to extend the algorithm, because each of these extensions leads to undecidability of the problem. On the other hand, we extend the algorithm to the calculus with name restriction and logic with new constructs for reasoning about restricted names.}, } @INPROCEEDINGS{CharatonikTalbot2002, AUTHOR = {Charatonik, Witold and Talbot, Jean-Marc}, EDITOR = {Tison, Sophie}, TITLE = {Atomic Set Constraints with Projection}, BOOKTITLE = {Rewriting Techniques and Applications. 13th International Conference, RTA 2002}, PADDRESS = {Berlin, Germany}, ADDRESS = {Copenhagen, Denmark}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2378}, ISBN = {3-540-43916}, YEAR = {2002}, PAGES = {311--325}, ABSTRACT = {We investigate a class of set constraints defined as atomic set constraints augmented with projection. This class subsumes some already studied classes such as atomic set constraints with left-hand side projection and INES constraints. All these classes enjoy a nice property that satisfiability can be performed in cubic time. This has be contrasted with several other classes of set constraints, such as definite set constraints and positive set constraints, for which satisfiability ranges from DEXPTIME-complete to NEXPTIME-complete. However, these latter classes allow set operators such as intersection or union which is not the case for the class studied here. In the case of atomic set constraints with projection one might expect that satisfiability remains polynomial. Unfortunately, we show that that the satisfiability problem for this class is no longer polynomial, but CoNP-hard. Furthermore, we devise a PSPACE algorithm to solve this satisfiability problem.}, } @ARTICLE{ChaudhuriDimopoulosZaroliagis-PPL96, AUTHOR = {Chaudhuri, Shiva and Dimopoulos, Yannis and Zaroliagis, Christos}, JOURNAL = {Parallel Processing Letters}, TITLE = {On the Parallel Complexity of Acyclic Logic Programs}, NUMBER = {2}, MONTH = {June}, VOLUME = {6}, ISBN = {0129-6264}, YEAR = {1996}, PAGES = {223--230}, ABSTRACT = {We investigate the parallel complexity of computing the stable model of acyclic general logic programs. Within this class of logic programs, we consider the cases of negative and definite logic programs. Both cases are proved to be P-complete. We prove the same for a related problem, namely that of computing the kernel of a directed acyclic graph.}, } @ARTICLE{chpl:93c, AUTHOR = {Chadha, Ritu and Plaisted, David A.}, JOURNAL = {Journal of Symbolic Computation}, TITLE = {On the mechanical derivation of loop invariants}, NUMBER = {5/6}, VOLUME = {15}, YEAR = {1993}, PAGES = {705--744}, ABSTRACT = {We describe an iterative algorithm for mechanically deriving loop invariants for the purpose of proving the partial correctness of programs. The algorithm is based on resolution and a novel unskolemization technique for deriving logical consequences of first-order formulas. Our method is complete in the sense that if a loop invariant exists for a loop in a given first-order language relative to a given finite set of first-order axioms, then the algorithm produces a loop invariant for that loop which can be used for proving the partial correctness of the program. Existing techniques in the literature are not complete.}, } @INPROCEEDINGS{chpl:94a, AUTHOR = {Chu, Heng and Plaisted, David A.}, EDITOR = {Bundy, Alan}, TITLE = {Semantically Guided First-Order Theorem Proving using Hyper-Linking}, BOOKTITLE = {Proceedings of the 12th International Conference on Automated Deduction (CADE-12)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Nancy, France}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {814}, YEAR = {1994}, PAGES = {192--206}, ABSTRACT = {We present a new procedure, {\em semantic hyper-linking} which uses semantics to guide an instance-based clause-form theorem prover. Semantics for the input clauses is given as input. During the search for the proof, ground instances of the input clauses are generated and new semantic structures are built based on the input semantics and a model of the ground clause set. A proof is found if the ground clause set is unsatisfiable. We give some results in proving hard theorems using semantic hyper-linking; no other special human guidance was given to prove these hard problems. We also show that our method is powerful even with a trivial semantics (that is, even with no guidance in the form of semantic information).}, } @ARTICLE{chpl:94b, AUTHOR = {Chadha, Ritu and Plaisted, David A.}, JOURNAL = {Journal of Logic Programming}, TITLE = {Correctness of unification without occur check in {P}rolog}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {2}, PUBLISHER = {Elsevier}, VOLUME = {18}, ISBN = {0743-1066}, YEAR = {1994}, PAGES = {99--122}, ABSTRACT = {For efficiency reasons, most Prolog implementations do not include an occur check in their unification algorithms and thus do not conform to the semantic model of first-order logic. We present a simple test which guarantees that unification without occur check is sound in programs satisfying the conditions of the test. We designate each argument position of every predicate as either an input or an output position and then describe a sufficient condition in terms of this designation for unification without occur check to be sound. Unification with occur check can be performed in places in the program where this condition is not satisfied. Two algorithms for implementing this test are described and compared.}, } @MASTERSTHESIS{Christen97, AUTHOR = {Christen, Michael}, TITLE = {A Calculus of Simplification for Superposition}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1997}, } @INPROCEEDINGS{CookPodelskiRybal2006, AUTHOR = {Cook, Byron and Podelski, Andreas and Rybalchenko, Andrey}, EDITOR = {Ball, Thomas and Jones, Robert B.}, TITLE = {Terminator: Beyond Safety}, BOOKTITLE = {Computer aided verification : 18th International Conference, CAV 2006}, PADDRESS = {Berlin, Germany}, ADDRESS = {Seattle, WA, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {4144}, ISBN = {978-3-540-37406-0}, YEAR = {2006}, PAGES = {415--418}, ABSTRACT = {Previous symbolic software model checkers (i.e., program analysis tools based on predicate abstraction, pushdown model checking and iterative counterexample-guided abstraction refinement, etc.) are restricted to safety properties. Terminator is the first software model checker for termination. It is now being used to prove that device driver dispatch routines always return to their caller (or return counterexamples if they if they fail to terminate). }, } @INPROCEEDINGS{CookPodelskiRybalchenkoSAS2005, AUTHOR = {Cook, Byron and Podelski, Andreas and Rybalchenko, Andrey}, EDITOR = {Hankin, Chris and Siveroni, Igor}, TITLE = {Abstraction-refinement for Termination}, BOOKTITLE = {Static analysis : 12th International Symposium, SAS 2005}, PADDRESS = {Berlin, Germany}, ADDRESS = {London, UK}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3672}, ISBN = {3-540-28584-9}, YEAR = {2005}, PAGES = {87--101}, } @INPROCEEDINGS{Cortier-et-al-99, AUTHOR = {Cortier, V. and Ganzinger, Harald and Jacquemard, Florent and Veanes, Margus}, EDITOR = {Wiedermann, Jiri and van Emde Boas, Peter and Nielsen, Mogen}, TITLE = {Decidable fragments of simultaneous rigid reachability}, BOOKTITLE = {Proceedings of the 26th International Colloquium on Automata, Languages and Programming (ICALP-99)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Prague, Czech Republik}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1644}, ISBN = {3-540-66224-3}, YEAR = {1999}, PAGES = {250--260}, NOTE = {Full version of this paper is available as MPI Research Report MPI-I-1999-2-004.}, ABSTRACT = {In this paper we prove decidability results of restricted fragments of simultaneous rigid reachability or SRR, that is the nonsymmetrical form of simultaneous rigid E-unification or SREU. The absence of symmetry enforces us to use different methods, than the ones that have been successful in the context of SREU (for example word equations). The methods that we use instead, involve finite (tree) automata techniques, and the decidability proofs provide precise computational complexity bounds. The main results are 1) monadic SRR with ground rule is PSPACE-complete, and 2) balanced SRR with ground rules is EXPTIME-complete. These upper bounds have been open already for corresponding fragments of SREU, for which only the hardness results have been known. The first result indicates the difference in computational power between fragments of SREU with ground rules and nonground rules, respectively, due to a straightforward encoding of word equations in monadic SREU (with nonground rules). The second result establishes the decidability and precise complexity of the largest known subfragment of nonmonadic SREU.}, } @ARTICLE{CPintersectionJ, AUTHOR = {Charatonik, Witold and Podelski, Andreas}, JOURNAL = {Information and Computation}, TITLE = {Set Constraints with Intersection}, ADDRESS = {New York, USA}, NUMBER = {2}, PUBLISHER = {Academic Press}, MONTH = {December}, VOLUME = {179}, ISBN = {0890-5401}, YEAR = {2002}, PAGES = {213--229}, ABSTRACT = { Set constraints are inclusions between expressions denoting sets of trees (over a given alphabet of constructor symbols). The efficiency of their satisfiability test is a central issue in set-based program analysis, their main application domain. We introduce the class of {\em set constraints with intersection}\/ (the only operators forming the expressions are constructors and intersection) and show that its satisfiability problem is DEXPTIME-complete. This is the first class of set constraints (over a general constructor alphabet) that falls into this complexity class. The solved form in our algorithm represents the least solution as a tree automaton and exhibits which variables denote the empty set. We furthermore prove that set constraints with intersection are equivalent to {\em definite set constraints}\/ (in expressive power, and the satisfiability problems are linearly inter-reducible). The class of definite set constraints was the first one for which the decidability question was solved; we hereby settle also the complexity question.}, } @UNPUBLISHED{CPR05:Terminator, AUTHOR = {Podelski, Andreas and Rybalchenko, Andrey and Cook, Byron}, TITLE = {Counterexample-Guided Abstraction Refinement for Termination}, MONTH = {January}, YEAR = {2005}, PAGES = {16}, } @ARTICLE{CP:95TCS, AUTHOR = {Podelski, Andreas and Smolka, Gert}, JOURNAL = {Theoretical Computer Science}, TITLE = {Situated Simplification}, NUMBER = {1}, MONTH = {February}, VOLUME = {173}, YEAR = {1997}, PAGES = {235--252}, NOTE = {Preliminary Version in Ugo Montanari, editor, Proceedings of the First International Conference on Principles and Practice of Constraint Programming (CP'95). Springer LNCS 976, 1995.}, ABSTRACT = { Testing satisfaction of guards is the essential operation of concurrent constraint programming ({\footnotesize CCP}) systems. We present and prove correct, for the first time, an incremental algorithm for the simultaneous tests of entailment and disentailment of rational tree constraints to be used in {\footnotesize CCP} systems with deep guards (\eg, in {\footnotesize AKL} or in Oz). The algorithm is presented as the {\em simplification\/} of the constraints which form the (possibly deep) guards and which are {\em situated\/} at different nodes in a tree (of arbitrary depth). The nodes correspond to local computation spaces. In this algorithm, a variable may have multiple bindings (which each represent a constraint on that same variable in a different node). These may be realized in various ways. We give a simple fixed-point algorithm and use it for proving that the tests implemented by another, practical algorithm are correct and complete for entailment and disentailment. We formulate the results in this paper for rational tree constraints; they can be adapted to finite and feature trees.}, } @INPROCEEDINGS{CunninghamGabbayOhlbach91a, AUTHOR = {Cunningham, J. and Gabbay, Dov M. and Ohlbach, Hans J{\"u}rgen}, TITLE = {Towards the {MEDLAR} Framework}, BOOKTITLE = {ESPRIT '91 Conference Proceedings}, INSTITUTION = {Directorate-General Telecommunications, Information Industries and Innovation}, PADDRESS = {Luxembourg}, ADDRESS = {Brussels, Belgium}, PUBLISHER = {Commission of the European Communities}, YEAR = {1991}, PAGES = {822--841}, ABSTRACT = {This is an outline description of work seeking an integrated framework for mechanising nonclassical logics. The particular logics and calculi we are concerned with are structured from the point of view of applications. As a first example for testing our prototype of the general framework, a generalised interpretation of modal logics is presented. Next, we introduce the methodology of {\it Labelled Deductive Systems\/}, demonstrating why this approach for a general framework is adequate to integrate various logical systems via a unified methodology. Finally, the need for different operational methods of solving problems in formal logic are briefly discussed in the context of an ambitious example suggested from MEDLAR case studies.}, } @INPROCEEDINGS{DammDischHungarPangPigorschSchollWaldmannWirtz2006, AUTHOR = {Damm, Werner and Disch, Stefan and Hungar, Hardi and Pang, Jun and Pigorsch, Florian and Scholl, Christoph and Waldmann, Uwe and Wirtz, Boris}, EDITOR = {Graf, Susanne and Zhang, Wenhui}, TITLE = {Automatic Verification of Hybrid Systems with Large Discrete State Space}, BOOKTITLE = {Automated Technology for Verification and Analysis, 4th International Symposium, ATVA 2006}, PADDRESS = {Berlin}, ADDRESS = {Beijing, China}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {4218}, ISBN = {3-540-47237-1}, YEAR = {2006}, PAGES = {276--291}, ABSTRACT = {We address the problem of model checking hybrid systems which exhibit nontrivial discrete behavior and thus cannot be treated by considering the discrete states one by one, as most currently available verification tools do. Our procedure relies on a deep integration of several techniques and tools. An extension of AND-Inverter-Graphs (AIGs) with first-order constraints serves as a compact representation format for sets of configurations which are composed of continuous regions and discrete states. Boolean reasoning on the AIGs is complemented by firstorder reasoning in various forms and on various levels. These include implication checks for simple constraints, test vector generation for fast inequality checks of boolean combinations of constraints, and an exact subsumption check for representations of two configurations.\par These techniques are integrated within a model checker for universal CTL. Technically, it deals with discrete-time hybrid systems with linear differentials. The paper presents the approach, its prototype implementation, and first experimental data.}, } @INPROCEEDINGS{DammRatschan2005a, AUTHOR = {Damm, Werner and Pinto, Guilherme and Ratschan, Stefan}, EDITOR = {Peled, Doron A and Tsay, Yih-Kuen}, TITLE = {Guaranteed Termination in the Verification of LTL Properties of Non-linear Robust Discrete Time Hybrid Systems}, BOOKTITLE = {Automated technology for verification and analysis : Third International Symposium, ATVA 2005}, PADDRESS = {Berlin, Germany}, ADDRESS = {Taipei, Taiwan}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3707}, ISBN = {3-540-29209-8}, YEAR = {2005}, PAGES = {99--113}, ABSTRACT = { We present a novel approach to the automatic verification and falsification of LTL requirements of non-linear discrete-time hybrid systems. The verification tool uses an interval-based constraint solver for non-linear robust constraints to compute incrementally refined abstractions. Although the problem is in general undecidable, we prove termination of abstraction refinement based verification and falsification of such properties for the class of \textit{robust non-linear hybrid systems}, thus significantly extending previous semi-decidability results. We argue, that safety critical control applications \textit{are} robust hybrid systems. We give first results on the application of this approach to a variant of an aircraft collision avoidance protocol. %}, } @ARTICLE{DelahayeJaumePrevosto2005, AUTHOR = {Delahaye, David and Jaume, Mathieu and Prevosto, Virgile}, JOURNAL = {Technique et Science Informatiques}, TITLE = {Coq, un outil pour l'enseignement}, NUMBER = {9}, PUBLISHER = {Herm{\`e}s Science}, VOLUME = {24}, YEAR = {2005}, PAGES = {1139--1160}, ABSTRACT = {In this article, we present the use of the Coq proof assistant with DESS (Master thesis) students. First, in the framework of a course of programming language semantics, Coq greatly helps the students to understand formal and abstract notions, such as induction, by binding them to more concrete terms. Next, a computer science project shows that Coq is also appropriate when dealing with larger problems. Last, we show how proofs developed by means of the Focal toolbox made it possible to get very valuable hints on the development of that system.}, } @INPROCEEDINGS{Delzanno1998, AUTHOR = {Delzanno, Giorgio}, EDITOR = {Galmiche, Didier}, TITLE = {Specification of Term Rewriting in Linear Logic}, BOOKTITLE = {Proceedings of Workshop on Proof-Search in Type-Theoretic Languages}, PADDRESS = {Amsterdam, the Netherlands}, ADDRESS = {Lindau, Germany}, PUBLISHER = {Elsevier}, SERIES = {Eletrical Notes in Theoretical Computer Science}, VOLUME = {17}, YEAR = {1998}, ABSTRACT = {We present an axiomatization of term rewriting systems in Forum, a presentation of linear logic in terms of uniform proofs, which allows us to relate provability and derivability in a natural way. The resulting theory can be used to prove properties of the original system. Vice versa the structure of the formulas used in the encoding suggests us a possible operational interpretation of Forum. The considered fragment turns out to be an extension of previously proposed multi-conclusion logics. }, } @ARTICLE{DelzannoBLM1999, AUTHOR = {Bugliesi, Michele and Delzanno, Giorgio and Liquori, Luigi and Martelli, Maurizio}, JOURNAL = {Journal of Logic and Computation}, TITLE = {Object Calculi in Linear Logic}, ADDRESS = {Oxford, UK}, NUMBER = {1}, PUBLISHER = {Oxford University Press}, MONTH = {April}, VOLUME = {10}, ISBN = {0955-792X}, YEAR = {2000}, PAGES = {75--104}, ABSTRACT = {Several calculi of objects have been studied in the recent literature, that support the central features of object-based languages: messages, inheritance, dynamic dispatch, object update and object-extension. We show that a complete semantic account of these features may be given in a fragment of higher-order linear logic. }, } @INPROCEEDINGS{DelzannoBMMZ1999, AUTHOR = {Bozzano, Marco and Delzanno, Giorgio and Martelli, Maurizio and Mascardi, Viviana and Zini, Floriano}, EDITOR = {Gupta, Gopal}, TITLE = {Multi-Agent Systems Development as a Software Engineering Enterprise}, BOOKTITLE = {Proceedings of the 1st International Workshop on Practical Aspects of Declarative Languages (PADL-99)}, ORGANIZATION = {Compulog Americas and Association for Logic Programming (ALP)}, PADDRESS = {Berlin, Germany}, ADDRESS = {San Antonio, Texas, USA}, PUBLISHER = {Springer}, MONTH = {October}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1551}, ISBN = {3-540-65527-1}, YEAR = {1999}, PAGES = {46--60}, ABSTRACT = {Multi-Agent Systems are receiving a wide consensus since they provide an ideal level of abstraction for modelling complex applications, where distributed and heterogeneous entities need to cooperate for achieving a common goal, or to concur for the control of shared resources. This paper proposes a declarative framework for developing multi-agent systems which adopts a logic-based formal approach for the specification and testing of software prototypes.}, } @INCOLLECTION{DelzannoBMMZb1999, AUTHOR = {Bozzano, Marco and Delzanno, Giorgio and Martelli, Maurizio and Mascardi, Viviana and Zini, Floriano}, EDITOR = {Apt, K. and Marek, V. W. and Truszczynski, M. and Warren, D. S.}, TITLE = {Logic Programming and Multi-Agent Systems: a Synergic Combination for Applications and Semantics}, BOOKTITLE = {The Logic Programming Paradigm: a 25-Year Perspective}, CHAPTER = {1}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, MONTH = {January}, SERIES = {Artificial Intelligence}, ISBN = {3-540-65463-1}, YEAR = {1999}, PAGES = {5--32}, } @INPROCEEDINGS{DelzannoEsparzaPodelski99, AUTHOR = {Delzanno, Giorgio and Esparza, Javier and Podelski, Andreas}, EDITOR = {Flum, J{\"o}rg and Rodr{\'i}guez-Artalejo, Mario}, TITLE = {Constraint-Based Analysis of Broadcast Protocols}, BOOKTITLE = {Proceedings of the 13th International Workshop on Computer Science Logic (CSL-99), 8th Annual Conference on the EACSL}, PADDRESS = {Berlin, Germany}, ADDRESS = {Madrid, Spain}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1683}, ISBN = {3-540-66536-6}, YEAR = {1999}, PAGES = {50--66}, } @ARTICLE{DelzannoGM1999, AUTHOR = {Delzanno, Giorgio and Galmiche, Didier and Martelli, Maurizio}, JOURNAL = {Mathematical Structures in Computer Science}, TITLE = {A specification logic for concurrent object-oriented programming}, ADDRESS = {Cambridge, UK}, NUMBER = {3}, PUBLISHER = {Cambridge University Press}, VOLUME = {9}, YEAR = {1999}, PAGES = {253--286}, ABSTRACT = {The paper focuses on the use of linear logic as a specification language of the operational semantics of advanced concepts of programming such as concurrency and object-orientation. Our approach is based on a refinement of linear logic sequent-calculi based on the proof-theoretic characterization of logic programming. A well-founded combination of higher-order logic programming and linear logic will be used to give an accurate encoding of the traditional features of concurrent object-oriented programming languages whose corner-stone is the notion of {\em encapsulation}.}, } @INPROCEEDINGS{DelzannoRaskinTACAS2000, AUTHOR = {Delzanno, Giorgio and Raskin, Jean-Fran{\c{c}}ois}, EDITOR = {Graf, Susann and Schwartzbach, Michael I.}, TITLE = {Symbolic Representation of Upward-Closed Sets}, BOOKTITLE = {Proceedings of the 6th Conference on Tools and Algorithms for Construction and Analysis of Systems (TACAS-00); Held as Part of the European Joint Conferences on the Theory and Practice of Software (ETAPS-00)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1785}, ISBN = {3-540-67282-6}, YEAR = {2000}, PAGES = {426--440}, ABSTRACT = {Abstract. The control state reachability problem is decidable for well-structured infinite-state systems like unbounded Petri Nets, Vector Addition Systems, Lossy Petri Nets, and Broadcast Protocols. An abstract algorithm that solves the problem is given in [ACJT96,FS99]. The algorithm computes the closure of the predecessor operator w.r.t. a given upward-closed set of target states. When applied to this class of verification problems, traditional (infinite-state) symbolic model checkers suffer from the state explosion problem even for very small examples. We provide BDD-like data structures to represent in a compact way collections of upwards closed sets over numerical domains. This way, we turn the abstract algorithm of [ACJT96,FS99] into a practical method. Preliminary experimental results indicate the potential usefulness of our method. }, } @INPROCEEDINGS{deNivelle1999direct, AUTHOR = {de Nivelle, Hans and Areces, Carlos and de Rijke, Maarten}, EDITOR = {Ganzinger, Harald}, TITLE = {Prefixed Resolution: A Resolution Method for Modal and Description Logics}, BOOKTITLE = {Proceedings of the 16th International Conference on Automated Deduction (CADE-16)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Trento, Italy}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1632}, ISBN = {3-540-66222-7}, YEAR = {1999}, PAGES = {187--201}, ABSTRACT = {We provide a resolution-based proof procedure for modal and description logics that improves on previous proposals in a number of important ways. First, it avoids translations into large undecidable logics, and works directly on modal or description logic formulas instead. Second, by using labeled formulas, it avoids the complexities of earlier propositional resolution-based methods for modal logic. Third, it provides a method for manipulating so-called assertional information in the description-logic setting. And fourth, we believe that it combines ideas from the method of prefixes used in tableaux and resolution in such a way that some of the heuristics and optimizations devised in either field are applicable.}, } @ARTICLE{deNivelle2000, AUTHOR = {de Nivelle, Hans}, JOURNAL = {Annals of Pure and Applied Logic}, TITLE = {Deciding the {E}-plus class by an a posteriori, liftable order}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {1}, PUBLISHER = {Elsevier}, VOLUME = {88}, YEAR = {2000}, PAGES = {219--232}, } @INPROCEEDINGS{deNivelle2000a, AUTHOR = {de Nivelle, Hans and Bezem, Marc and Hendriks, Dimitri}, EDITOR = {McAllester, David}, TITLE = {Automated Proof Construction in Type Theory Using Resolution}, BOOKTITLE = {Proceedings of the 17th International Conference on Automated Deduction (CADE-17)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Carnegie Mellon University, Pittsburgh, PA, USA}, PUBLISHER = {Springer}, MONTH = {June}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1831}, ISBN = {3-540-67664-3}, YEAR = {2000}, PAGES = {148--163}, ABSTRACT = {We provide techniques to integrate resolution logic with equality into type theory. The results may be rendered as follows: - A clausification procedure in type theory, equipped with a correctness proof, all encoded using higher-order primitive recursion. - A novel representation of clauses in minimal logic such that the lambda-representation of resolution proofs is linear in the size of the premises. - A translation of resolution proofs into lambda terms, yielding a verification procedure for those proofs - The prower of resolution theorem provers becomes available in interactive proof construction systems based on type theory.}, } @INPROCEEDINGS{deNivelle2000b, AUTHOR = {de Nivelle, Hans}, EDITOR = {Faller, Martina and Kaufmann, Stefan and Pauly, Marc}, TITLE = {An Overview of Resolution Decision Procedures}, BOOKTITLE = {Formalizing the Dynamics of Information}, PADDRESS = {Stanford, USA}, ADDRESS = {Stanford University, Palo Alto, USA}, PUBLISHER = {Center for the Study of Language and Information}, SERIES = {CSLI Publications}, VOLUME = {91}, ISBN = {1-57586-239-5}, YEAR = {2000}, PAGES = {115--130}, ABSTRACT = {In the paper I give a unified treatment of several first order decidable classes, using resolution decision procedures.}, } @ARTICLE{deNivelle2000c, AUTHOR = {de Nivelle, Hans and Hustadt, Ullrich and Schmidt, Renate A.}, JOURNAL = {Logic Journal of the IGPL}, TITLE = {Resolution-Based Methods for Modal Logics}, ADDRESS = {Oxford, UK}, NUMBER = {3}, PUBLISHER = {Oxford University Press}, MONTH = {May}, VOLUME = {8}, ISBN = {1367-0751}, YEAR = {2000}, PAGES = {265--292}, NOTE = {%My name is misspelt as 'Nivellle'}, ABSTRACT = {We give an overview of resolution based methods for propositional multimodal logics, and description logics. The strategies that we give are decision procedures. That means that they are guaranteed to terminate in all cases. }, } @INPROCEEDINGS{deNivelle2001, AUTHOR = {de Nivelle, Hans and Pratt-Hartmann, Ian}, EDITOR = {Gor{\'e}, Rajeev and Leitsch, Alexander and Nipkow, Tobias}, TITLE = {A Resolution-Based Decision Procedure for the Two-Variable Fragment with Equality}, BOOKTITLE = {Automated reasoning : First International Joint Conference, IJCAR 2001}, PADDRESS = {Berlin, Germany}, ADDRESS = {Siena, Italy}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2083}, ISBN = {3-540-42254-4}, YEAR = {2001}, PAGES = {211--225}, ABSTRACT = {The two-variable fragment of first-order logic is the set of formulas that do not contain function symbols, that possibly contain equality, and that contain at most two variables. This paper shows how resolution theorem-proving techniques can be used to provide an algorithm for deciding whether or not any given formula in the two-variable fragment is satisfiable. Previous resolution-based techniques could deal only with the equality-free subset of the two-variable fragment. }, } @INPROCEEDINGS{deNivelle2001lpar, AUTHOR = {de Nivelle, Hans}, EDITOR = {Nieuwenhuis, Robert and Voronkov, Andrei}, TITLE = {Splitting through New Proposition Symbols}, BOOKTITLE = {Proceedings of the 8th International Conference on Logic for Programming, Artificial Intelligence, and Reasoning (LPAR-2001)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Havana, Cuba}, PUBLISHER = {Springer}, MONTH = {December}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2250}, ISBN = {3-540-42957-3}, YEAR = {2001}, PAGES = {172--185}, ABSTRACT = {This paper presents ways of simulating splitting through new propositional symbols. The contribution of the paper is that the method presented here does not loose backward redundancy. We give a general method of obtaining a calculus with splitting by adjoining splitting symbols to an arbitrary resolution refinement. We then prove a relative completeness theorem: Every saturated set of clauses of the resolution calculus with adjoined proposition symbols contains a saturated set of the original resolution refinement without adjoined symbols.}, } @ARTICLE{deNivelle2001slp, AUTHOR = {de Nivelle, Hans and Blackburn, Patrick and Bos, Johan and Kohlhase, Michael}, JOURNAL = {Studies in Linguistics and Philosophy, Computing Meaning}, TITLE = {Inference and Computational Semantics}, ADDRESS = {Dordrecht, The Netherlands}, NUMBER = {2}, PUBLISHER = {Kluwer}, VOLUME = {77}, ISBN = {1-4020-0175-4}, YEAR = {2001}, PAGES = {11--28}, } @INPROCEEDINGS{deNivelle2002a, AUTHOR = {de Nivelle, Hans}, EDITOR = {Bradfield, Julian}, TITLE = {Extraction of Proofs from the Clausal Normal Form Transformation}, BOOKTITLE = {Computer Science Logic : 16th International Workshop, CSL 2002, 11th Annual Conference of the EACSL}, PADDRESS = {Berlin, Germany}, ADDRESS = {Edinburgh, UK}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2471}, ISBN = {3-540-44240-5}, YEAR = {2002}, PAGES = {584--598}, ABSTRACT = {We give techniques for extracting proofs from the Clausal Normal Form transformation. We discuss and solve three technical problems: {\bf (1)}. How to handle the introduction of definitions and Skolem functions. {\bf (2)}. How to generate short (linear size) proofs. {\bf (3)}. How to handle optimized Skolemization. We reduce it to standard Skolemization.}, } @ARTICLE{deNivelle2002b, AUTHOR = {Bezem, Marc and Hendriks, Dimitri and de Nivelle, Hans}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {Automated Proof Construction in Type Theory using Resolution}, ADDRESS = {Dordrecht, the Netherlands}, NUMBER = {3/4}, PUBLISHER = {Kluwer}, MONTH = {December}, VOLUME = {29}, ISBN = {0168-7433}, YEAR = {2002}, PAGES = {253--275}, ABSTRACT = {We provide techniques to integrate resolution logic with equality in type theory. The results may be rendered as follows: {\bf (1)}. A clausification procedure in type theory, equipped with a correctness proof, all encoded using higher-order primitive recursion. {\bf (2)}. A novel representation of clauses in minimal logic such that the $ \lambda $-representation of resolution steps is linear in the size of the premisses. {\bf (3)}. Availability of the power of resolution theorem provers in interactive proof construction systems based on type theory.}, } @ARTICLE{deNivelle2003a, AUTHOR = {de Nivelle, Hans and de Rijke, Maarten}, JOURNAL = {Journal of Symbolic Computation}, TITLE = {Deciding the Guarded Fragments by Resolution}, ADDRESS = {Amsterdam, The Netherlands}, PUBLISHER = {Elsevier}, MONTH = {January}, VOLUME = {35}, ISBN = {0747-7171}, YEAR = {2003}, PAGES = {21--58}, ABSTRACT = {We give resolution based decision procedures for both the strictly guarded fragment and the loosely guarded fragment of first-order logic. We prove that the decision procedures are in 2EXPTIME, which is theoretically optimal.}, } @INPROCEEDINGS{deNivelle2003b, AUTHOR = {de Nivelle, Hans}, EDITOR = {Baader, Franz}, TITLE = {Translation of Resolution Proofs into Short First-Order Proofs without Choice Axioms}, BOOKTITLE = {Automated deduction, CADE-19 : 19th International Conference on Automated Deduction}, PADDRESS = {Berlin, Germany}, ADDRESS = {Miami, USA}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2741}, ISBN = {3-540-40559-3}, YEAR = {2003}, PAGES = {365--379}, ABSTRACT = {We present a way of transforming a resolution proof containing Skolemization into a natural deduction proof of the same formula but not using Skolemization. The size of the proof increases only moderately (polynomially). This makes it possible to translate the output of a resolution theorem prover into a purely first-order proof that is moderate in size.}, } @INPROCEEDINGS{deNivelle2003c, AUTHOR = {de Nivelle, Hans}, EDITOR = {Konev, Boris and Schmidt, Renate}, TITLE = {Implementing the clausal normal form transformation with proof generation}, BOOKTITLE = {Fourth Workshop on the Implementation of Logics}, PADDRESS = {Liverpool, UK}, ADDRESS = {Almaty, Kazachstan}, PUBLISHER = {University of Liverpool, University of Manchester}, YEAR = {2003}, PAGES = {69--83}, ABSTRACT = { We explain how to implement the clausal normal form transformation with proof generation. We present a convenient data structure for sequent calculus proofs, which will be used for representing the generated proofs. The data structure allows easy proof checking and generation of proofs. In addition, it allows convenient implementation of proof normalization, which is necessary in order to keep the size of the generated proofs acceptable.}, } @ARTICLE{deNivelle2005a, AUTHOR = {de Nivelle, Hans}, JOURNAL = {Information and Computation}, TITLE = {Translation of Resolution Proofs into Short First-Order Proofs without Choice Axioms}, ADDRESS = {Amsterdam, The Netherlands}, NUMBER = {1}, PUBLISHER = {Elsevier}, MONTH = {April}, VOLUME = {199}, YEAR = {2005}, PAGES = {24--54}, ABSTRACT = {We present a way of transforming a resolution-style proof containing Skolemization into a natural deduction proof without Skolemization. The size of the proof increases only moderately (polynomially). This makes it possible to translate the output of a resolution theorem prover into a purely first-order proof that is moderate in size.}, } @PROCEEDINGS{deNivelle2006a, EDITOR = {Ahrendt, Wolfgang and Baumgartner, Peter and de Nivelle, Hans}, TITLE = {IJCAR'06 Workshop : Disproving'06: Non-Theorems, Non-Validity, Non-Provability}, PADDRESS = {Seattle, USA}, ADDRESS = {Seattle, USA}, PUBLISHER = {The 2006 Federated Logic Conference}, YEAR = {2006}, PAGES = {99}, ABSTRACT = {The volume contains 9 contributed papers.}, } @INPROCEEDINGS{deNivelle2006b, AUTHOR = {de Nivelle, Hans and Baumgartner, Peter and Fuchs, Alexander and Tinelli, Cesare}, EDITOR = {Ahrendt, Wolfgang and Baumgartner, Peter and de Nivelle, Hans}, TITLE = {Computing Finite Models by Reduction to Function-Free Clause Logic}, BOOKTITLE = {IJCAR'06 Workshop : Disproving'06: Non-Theorems, Non-Validity, Non-Provability}, PADDRESS = {Seattle, USA}, ADDRESS = {Seattle, USA}, PUBLISHER = {The 2006 Federated Logic Conference}, MONTH = {August}, YEAR = {2006}, PAGES = {82--95}, ABSTRACT = {We propose to reduce model search to a sequence of satisfiability problems made of function-free clause sets, and to apply efficient theorem provers capable of deciding such problems on them. The main motivation for this method is the fact that first-order clause sets grow more slowly than their propositional counterparts, thus allowing for more space-efficient reasoning. We describe the method in detail, and show how it is integrated into Darwin, which is an implementation of the model evolution calculus. Although we used Darwin, the results are general, as our approach can be used in principle with every system that decides the satisfiability of function-free first-order clause sets.}, } @TECHREPORT{deNivelleDemri2003a, AUTHOR = {de Nivelle, Hans and Demri, St{\'e}phane}, TITLE = {Deciding regular grammar logics with converse through first-order logic}, INSTITUTION = {Laboratoire de Sp{\'e}cification et de V{\'e}rification, ENS Cachan}, TYPE = {research report}, ADDRESS = {Cachan, France}, NUMBER = {LSV-03-4}, YEAR = {2003}, PAGES = {29}, ABSTRACT = {We provide a simple translation of the satisfiability problem for grammar logics with converse into GF2 which is the intersection of the guarded fragment and the 2-variable fragment of first-order logic. This translation is theoretically interesting because it translates modal logics with certain frame conditions into first-order logic, without explicitly expressing the frame conditions. A consequence of the translation is that the general satisfiability problem for regular grammar logics with converse is in EXPTIME. This extends a previous result of the first author for grammar logics without converse. Using the same method, we show how some other modal logics can be naturally translated into GF2, including nominal tense logics and intuitionistic logic. In our view, the results in this paper show that the natural first-order fragment corresponding to regular grammar logics is simply GF2 without extra machinery such as fixed point-operators. This answers an open question posed in [Demri'01].}, } @INPROCEEDINGS{deNivelleDemri2003c, AUTHOR = {de Nivelle, Hans and Demri, St{\'e}phane}, EDITOR = {Areces, Carlos and Blackburn, Patrick}, TITLE = {Deciding Modal Logics through Relational Translations into {GF2}}, BOOKTITLE = {Proceedings of the 3rd Methods for Modalities Workshop}, PADDRESS = {Nancy, France}, ADDRESS = {Nancy, France}, PUBLISHER = {Loria}, YEAR = {2003}, PAGES = {15--30}, ABSTRACT = {We provide a simple translation from the satisfiability problem for regular grammar logics with converse into {GF2}, the intersection of the guarded fragment and the 2-variable fragment of first-order logic. The translation is theoretically interesting because it translates modal logics with certain frame conditions into first-order logic, without explicitly expressing the frame conditions. Using the same method, one can show that other modal logics can be naturally translated into {GF2}, including nominal tense logics and intuitionistic propositional logic. In our view, the results in this paper provide strong evidence that the natural first-order fragment corresponding to modal logics, is {GF2}.}, } @ARTICLE{deNivelleDemri2005, AUTHOR = {de Nivelle, Hans and Demri, St{\'e}phane}, JOURNAL = {Journal of Logic, Language and Information}, TITLE = {Deciding Regular Grammar Logics with Converse through First-Order Logic}, ADDRESS = {Dordrecht, The Netherlands}, NUMBER = {3}, PUBLISHER = {Springer}, MONTH = {June}, VOLUME = {14}, ISBN = {0925-8531}, YEAR = {2005}, PAGES = {289--329}, ABSTRACT = {We provide a simple translation of the satisfiability problem for regular grammar logics with converse into GF2, the intersection of the guarded fragment and the 2-variable fragment of first-order logic. The translation is theoretically interesting, because it translates modal logics with certain frame conditions into first-order logic, without explicitly expressing these frame conditions. It is practically relevant, because it makes it possible to use a decision procedure for the guarded fragment in order to decide regular grammar logics with converse. The class of regular grammar logics includes numerous logics from various application domains. In our view, the results in this paper show that the natural first-order fragment corresponding to regular grammar logics is simply GF2, without extra machinery, as for example fixed point operators.}, } @INPROCEEDINGS{deNivelleMeng2006a, AUTHOR = {de Nivelle, Hans and Meng, Jia}, EDITOR = {Furbach, Ulrich and Shankar, Natarajan}, TITLE = {Geometric Resolution: A Proof Procedure Based on Finite Model Search}, BOOKTITLE = {Automated reasoning : Third International Joint Conference, IJCAR 2006}, PADDRESS = {Berlin, Germany}, ADDRESS = {Seattle, WA, USA}, PUBLISHER = {Springer}, MONTH = {August}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {4130}, ISBN = {978-3-540-37187-8}, YEAR = {2006}, PAGES = {303--317}, ABSTRACT = {We present a proof search procedure which is complete for first-order logic, but which also can be used when searching for finite models. The procedure uses a normal form that is closely related to geometric formulas. For this reason, we call the procedure geometric resolution. We expect that the procedure can be used as an efficient proof search procedure for first-order logic. We will point out how the procedure can be implemented in such a way that it is complete for finite models without loosing completeness for unsatisfiability. We will also discuss two refinements of the initial procedure, namely subsumption and functional reduction, and prove their completeness. Finally, we will discuss how the calculus can be implemented.}, } @MISC{deNivelleMeng2006b, AUTHOR = {de Nivelle, Hans and Meng, Jia}, TITLE = {Geo 2006j}, HOWPUBLISHED = {can be obtained from my homepage}, MONTH = {September}, YEAR = {2006}, ABSTRACT = {Geo is a prover for full-first order logic. It is writen in C++. It is based on a new calculus, which is called geometric resolution, and which is described in our paper at IJCAR 2006. The calculus is called geometric resolution because it uses an internal format that is closely related to geometric logic. It should be equally good in finding proofs as in finding finite models. Geo 2006i won the best newcomer award at CASC 2006. geo2006j is a slight improvement of geo2006i.}, } @INPROCEEDINGS{DeNivellePiskac2005a, AUTHOR = {de Nivelle, Hans and Piskac, Ruzica}, EDITOR = {Aichernig, Bernhard K. and Beckert, Bernhard}, TITLE = {Verification of an Off-Line Checker for Priority Queues}, BOOKTITLE = {Third IEEE International Conference on Software Engineering and Formal Methods (SEFM 2005)}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Koblenz}, PUBLISHER = {IEEE}, ISBN = {0-7695-2435-4}, YEAR = {2005}, PAGES = {210--219}, } @PROCEEDINGS{deNivelleSchulz2001, EDITOR = {de Nivelle, Hans and Schulz, Stephan}, TITLE = {Proceedings of the 2nd International Workshop on the Implementation of Logics}, PADDRESS = {Saarbr{\"u}cken, Germany}, ADDRESS = {Havanna, Cuba}, NUMBER = {MPI-I-2001-2-006}, PUBLISHER = {Max-Planck-Institut f{\"u}r Informatik}, SERIES = {Research Report}, ISBN = {0946-011X}, YEAR = {2001}, PAGES = {102}, } @INPROCEEDINGS{deRJaeLeeMan02, AUTHOR = {de Raedt, Luc and Jaeger, Manfred and Lee, Sau Dan and Mannila, Heikki}, TITLE = {A Theory of Inductive Query Answering}, BOOKTITLE = {Proceedings of the 2002 IEEE International Conference on Data Mining (ICDM'02)}, ORGANIZATION = {IEEE Computer Society}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Maebashi City, Japan}, PUBLISHER = {IEEE}, MONTH = {December}, ISBN = {0-7695-1754-4}, YEAR = {2002}, PAGES = {123--130}, ABSTRACT = {We introduce the boolean inductive query evaluation problem, which is concerned with answering inductive que ries that are arbitrary boolean expressions over monotonic and anti-monotonic predicates. Secondly, we develop a d ecomposition theory for inductive query evaluation in which a boolean query $Q$ is reformulated into $k$ sub-queries $Q_i = Q_A \wedge Q_M$ that are the conjunction of a monotonic and an anti-monotonic predicate. The solution to each sub-query can be represented using a version space. We investigate how the number of version spaces $k$ needed to answer the query can be minimized. Thirdly, for the pattern domain of strings, we show how the version spaces can be represented using a novel data structure, called the version space tree, and can be computed using a variant of the famous Apriori alg orithm. Finally, we present some experiments that validate the approach.}, } @INPROCEEDINGS{DGNVV98a, AUTHOR = {Degtyarev, Anatoli and Gurevich, Yuri and Narendran, Paliath and Veanes, Margus and Voronkov, Andrei}, EDITOR = {Nipkow, Tobias}, TITLE = {The Decidability of Simultaneous Rigid {E}-Unification with One Variable}, BOOKTITLE = {Proceedings of the 9th International Conference on Rewriting Techniques and Applications (RTA-98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Tsukuba, Japan}, PUBLISHER = {Springer}, MONTH = {March}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1379}, ISBN = {3-540-64301-X}, YEAR = {1998}, PAGES = {181--195}, ABSTRACT = {We show that simultaneous rigid $E$-unification, or SREU for short, is decidable and in fact EXPTIME-complete in the case of one variable. This result implies that the $\forall^*\exists\forall^*$ fragment of intuitionistic logic with equality is decidable. Together with a previous result regarding the undecidability of the $\exists\exists$-fragment, we obtain {\em a complete classification of decidability of the prenex fragment of intuitionistic logic with equality, in terms of the quantifier prefix.} It is also proved that SREU with one variable and a constant bound on the number of rigid equations is P-complete.}, } @ARTICLE{DGNVV99, AUTHOR = {Degtyarev, Anatoli and Gurevich, Yuri and Narendran, Paliath and Veanes, Margus and Voronkov, Andrei}, JOURNAL = {Theoretical Computer Science}, TITLE = {Decidability and Complexity of Simultaneous Rigid {E}-unification with One Variable and Related Results}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {1/2}, PUBLISHER = {Elsevier}, MONTH = {July}, VOLUME = {243}, YEAR = {2000}, PAGES = {167--184}, ABSTRACT = {We show that simultaneous rigid $E$-unification, or SREU for short, is decidable and in fact EXPTIME-complete in the case of one variable. This result implies that the A*EA*-fragment of intuitionistic logic with equality is decidable. Together with a previous result regarding the undecidability of the EE-fragment, we obtain {\em a complete classification of decidability of the prenex fragment of intuitionistic logic with equality, in terms of the quantifier prefix.} It is also proved that SREU with one variable and a constant bound on the number of rigid equations is P-complete. Moreover, we consider a case of SREU where one allows several variables, but each rigid equation either contains one variable, or has a ground left-hand side and an equality between two variables as a right-hand side. We show that SREU is decidable also in this restricted case.}, } @ARTICLE{dim92, AUTHOR = {Dimopoulos, Yannis and Magirou, Vangelis}, JOURNAL = {Information and Computation}, TITLE = {A Graph Theoretic Approach to Default Logic}, NUMBER = {2}, MONTH = {August}, VOLUME = {112}, ISBN = {0890-5401}, YEAR = {1994}, PAGES = {239--256}, ABSTRACT = {A network representation of propositional seminormal disjunction-free default theories is presented, leading to a graph-theoretic approach to their analysis. The problem of finding an extension is proved to be equivalent to that of determining a kernel for a corresponding graph, allowing stronger complexity results as well as new conditions for the existence of extensions.}, } @INPROCEEDINGS{dim94a, AUTHOR = {Dimopoulos, Yannis}, EDITOR = {Ras, Z. and Zemankova, M.}, TITLE = {Classical Methods in Nonmonotonic Reasoning}, BOOKTITLE = {Proceedings of the 8th International Symposium on Methodologies for Intelligent Systems (ISMIS'94)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Charlotte, North Carolina}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {869}, YEAR = {1994}, PAGES = {500--510}, NOTE = {Extended version available as Research Report MPI-I-94-229, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken}, ABSTRACT = {In this paper we present and compare some classical problem solving methods for computing the stable models of logic programs with negation. In particular linear programming, propositional satisfiability, constraint satisfaction, and graph algorithms are considered. Central to our approach is the representation of the logic program by means of a graph. It turns out that the graph model offers the possibility of the effective use of these problem solving approaches.}, } @INPROCEEDINGS{dim94c, AUTHOR = {Dimopoulos, Yannis}, EDITOR = {MacNish, Craig and Pearce, David and Pereira, Lu{\'i}s Moniz}, TITLE = {The Computational Value of Joint Consistency}, BOOKTITLE = {Logics in Artificial Intelligence: Proceedings of the JELIA'94}, PADDRESS = {Berlin, Germany}, ADDRESS = {York, UK}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {838}, YEAR = {1994}, PAGES = {50--65}, ABSTRACT = {In this paper we investigate the complexity of some recent reconstructions of Reiter's Default Logic using graph-theoretical structures. It turns out that requiring joint consistency of the justification of the applied rules has serious effects on the computational features of default reasoning. Namely, many of the intractability problems of Reiter's original approach, in some cases disappear in the new frameworks. However, interesting problems remain intractable. We also present a propositional semantics for those approaches, stemming from the translation of the graph structures into propositional logic. Finally, the constraint stable model semantics is introduced, and proved to be related to the notion of joint consistency.}, } @MASTERSTHESIS{Dimitrova2006, AUTHOR = {Dimitrova, Rayna}, TITLE = {Model Checking with Abstraction Refinement for Well-Structured Systems}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {June}, YEAR = {2006}, } @ARTICLE{Dimopoulos-93-mpii226-2-, AUTHOR = {Dimopoulos, Yannis and Magirou, Vangelis and Papadimitriou, Christos}, JOURNAL = {Annals of Mathematics and Artificial Intelligence}, TITLE = {On Kernels, Defaults and Even Graphs}, INSTITUTION = {Max-Planck-Institut f{\"u}r Informatik}, TYPE = {Technical Report}, ADDRESS = {Saarbr{\"u}cken}, NUMBER = {MPI-I-93-226}, YEAR = {1993}, NOTE = {To appear. Also available as Technical Report MPI-I-93-226}, ABSTRACT = {Extensions in prerequisite-free, disjunction-free default theories have been shown to be in direct correspondence with kernels of directed graphs; hence default theories without odd cycles always have a ``standard'' kind of an extension. We show that, although all ``standard'' extensions can be enumerated explicitly, several other problems remain intractable for such theories: Telling whether a non-standard extension exists, enumerating all extensions, and finding the minimal standard extension. We also present a new graph-theoretic algorithm, based on vertex feedback sets, for enumerating all extensions of a general prerequisite-free, disjunction-free default theory (possibly with odd cycles). The algorithm empirically performs well for quite large theories.}, } @INPROCEEDINGS{DMSSISAMC2005, AUTHOR = {Daum, Matthias and Maus, Stefan and Schirmer, Norbert and Seghir, Mohammed Nassim}, EDITOR = {Sutcliffe, Geoff and Voronkov, Andrei}, TITLE = {Integration of a Software Model Checker into Isabelle}, BOOKTITLE = {Logic for Programming, Artificial Intelligence, and Reasoning: 12th International Conference, LPAR 2005}, PADDRESS = {Berlin, Germany}, ADDRESS = {Montego Bay, Jamaica}, PUBLISHER = {Springer}, MONTH = {October}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {3835}, ISBN = {3-540-30553-X}, YEAR = {2005}, PAGES = {381--395}, ABSTRACT = {The paper presents a combination of interactive and automatic tools in the area of software verification. We have integrated a newly developed software model checker into an interactive verification environment for imperative programming languages. Although the problems in software verification are mostly too hard for full automation, we could increase the level of automated assistance by discharging less interesting side conditions. That allows the verification engineer to focus on the abstract algorithm, safely assuming unbounded arithmetic and unlimited buffers.}, } @ARTICLE{Domopoulos96, AUTHOR = {Dimopoulos, Yannis}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {On Computing Logic Programs}, NUMBER = {3}, PUBLISHER = {Kluwer}, VOLUME = {17}, ISBN = {0168-7433}, YEAR = {1996}, PAGES = {259--289}, } @INPROCEEDINGS{DomshlakHoffmann2006, AUTHOR = {Domshlak, Carmel and Hoffmann, J{\"o}rg}, EDITOR = {Long, Derek and Smith, Stephen F. and Borrajo, Daniel and McCluskey, Lee}, TITLE = {Fast Probabilistic Planning Through Weighted Model Counting}, BOOKTITLE = {Proceedings of the Sixteenth International Conference on Automated Planning and Scheduling (ICAPS 2006)}, PADDRESS = {Menlo Park, USA}, ADDRESS = {The English Lake District}, PUBLISHER = {AAAI}, ISBN = {978-1-57735-270-9}, YEAR = {2006}, PAGES = {243--252}, ABSTRACT = {We present a new algorithm for probabilistic planning with no observability. Our algorithm, called Probabilistic-FF, extends the heuristic forward-search machinery of Conformant-FF to problems with probabilistic uncertainty about both the initial state and action effects. Specifically, Probabilistic-FF combines Conformant-FF's techniques with a powerful machinery for weighted model counting in (weighted) CNFs, serving to elegantly define both the search space and the heuristic function. Our evaluation of Probabilistic-FF on several probabilistic domains shows an unprecedented, several orders of magnitude improvement over previous results in this area. }, } @ARTICLE{DP-STTT01, AUTHOR = {Delzanno, Giorgio and Podelski, Andreas}, JOURNAL = {International Journal on Software Tools for Technology Transfer (STTT)}, TITLE = {Constraint-based Deductive Model Checking}, ADDRESS = {Berlin, Germany}, NUMBER = {3}, PUBLISHER = {Springer}, VOLUME = {3}, YEAR = {2001}, PAGES = {250--270}, } @ARTICLE{Eisenbrand1999, AUTHOR = {Eisenbrand, Friedrich}, JOURNAL = {Combinatorica}, TITLE = {On the Membership Problem for the Elementary Closure of a Polyhedron}, NUMBER = {2}, PUBLISHER = {J{\'a}nos Bolyai Mathematical Society}, VOLUME = {19}, YEAR = {1999}, PAGES = {297--300}, } @PHDTHESIS{Eisenbrand2000, AUTHOR = {Eisenbrand, Friedrich}, TITLE = {{Gomory-Chv{\'a}tal} Cutting planes and the Elementary Closure of Polyhedra}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {July}, YEAR = {2000}, } @ARTICLE{Eisenbrand2001, AUTHOR = {Eisenbrand, Friedrich}, JOURNAL = {Information Processing Letters}, TITLE = {Short vectors of planar integral lattices via continued fractions}, VOLUME = {79}, YEAR = {2001}, PAGES = {121--126}, } @INPROCEEDINGS{EisenSchulz1999, AUTHOR = {Eisenbrand, Friedrich and Schulz, Andreas S.}, EDITOR = {Cornu{\'e}jols, G{\'e}rard and Burkard, Rainer E. and Woeginger, Gerhard J.}, TITLE = {Bounds on the {Chv{\'a}tal} Rank of Polytopes in the 0/1-Cube}, BOOKTITLE = {Proceedings of the 7th Conference on Integer Programming and Combinatorial Optimization (IPCO-99)}, TYPE = {Extended Abstract}, PADDRESS = {Berlin, Germany}, ADDRESS = {Graz, Austria}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1610}, ISBN = {3-540-66019-4}, YEAR = {1999}, PAGES = {137--150}, } @INCOLLECTION{EisingerNonnengartPraecklein92, AUTHOR = {Eisinger, Norbert and Nonnengart, Andreas and Pr{\"a}cklein, Axel}, EDITOR = {Bl{\"a}sius, K.H. and B{\"u}rckert, Hans-J{\"u}rgen}, TITLE = {{Termersetzungssysteme}}, BOOKTITLE = {Deduktionssysteme -- Automatisierung des logischen Denkens}, CHAPTER = {III.4}, ADDRESS = {M{\"u}nchen, Germany}, PUBLISHER = {Oldenbourg}, EDITION = {2}, ISBN = {3-486-22033-0}, YEAR = {1992}, PAGES = {126--149}, NOTE = {This is the modified and extended version of the corresponding chapter of the first edition of this book.}, } @INPROCEEDINGS{EisingerOhlbach93, AUTHOR = {Eisinger, Norbert and Ohlbach, Hans J{\"u}rgen}, EDITOR = {Gabbay, Dov M. and Hogger, C. J. and Robinson, J. A.}, TITLE = {Deduction Systems Based on Resolution}, BOOKTITLE = {Handbook of Logic in Artificial Intelligence and Logic Programming}, PADDRESS = {Oxford, UK}, ADDRESS = {?}, PUBLISHER = {Oxford University Press}, VOLUME = {I, Logical Foundations}, ISBN = {0-19-853745-X}, YEAR = {1993}, PAGES = {184--271}, NOTE = {Also available as Research Report MPI-I-91-217}, ABSTRACT = {A general theory of deduction systems is presented. The theory is illustrated with deduction systems based on the resolution calculus, in particular with clause graphs. This theory distinguishes four constituents of a deduction system: \begin{itemize} \item the logic, which establishes a notion of semantic entailment; \item the calculus, whose rules of inference provide the syntactic counterpart of entailment; \item the logical state transition system, which determines the representation of formulae or sets of formulae together with their interrelationships, and also may allow additional operations reducing the search space; \item the control, which comprises the criteria used to choose the most promising from among all applicable inference steps. \end{itemize} Much of the standard material on resolution is presented in this framework. For the last two levels many alternatives are discussed. Appropriately adjusted notions of soundness, completeness, confluence, and Noetherianness are introduced in order to characterize the properties of particular deduction systems. For more complex deduction systems, where logical and topological phenomena interleave, such properties can be far from obvious.}, } @ARTICLE{EisingerOhlbachPraecklein91a, AUTHOR = {Eisinger, Norbert and Ohlbach, Hans J{\"u}rgen and Pr{\"a}cklein, Axel}, JOURNAL = {Artificial Intelligence}, TITLE = {Reduction Rules for Resolution Based Systems}, ADDRESS = {?}, VOLUME = {50}, YEAR = {1991}, PAGES = {141--181}, ABSTRACT = {Inference rules for resolution based systems can be classified into deduction rules, which add new objects, and reduction rules, which remove objects. Traditional reduction rules like subsumption do not actively contribute to a solution, but they help to avoid redundancies in the search space. We present a number of advanced reduction rules, which can cope with high degrees of redundancy and play a distinctly active part because they find trivial solutions on their own and thus relieve the control component for the deduction rules from low level tasks. We describe how these reduction rules can be implemented with reasonable efficiency in a clause graph resolution system, but they are not restricted to this particular representation.}, } @MASTERSTHESIS{Engel96, AUTHOR = {Engel, Thorsten}, TITLE = {Quantifier Elimination in Second-Order Predicate Logic}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1996}, } @INPROCEEDINGS{ER2001, AUTHOR = {Eisenbrand, Friedrich and Rote, G{\"u}nter}, EDITOR = {Gerards, Bert and Aardal, Karen}, TITLE = {Fast 2-variable integer programming}, BOOKTITLE = {Proceedings of the 8th Conference on Integer and Combinatorial Optimization (IPCO-01)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Utrecht, Netherlands}, PUBLISHER = {Springer}, MONTH = {June}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2081}, YEAR = {2001}, PAGES = {78--89}, } @INPROCEEDINGS{ER2001b, AUTHOR = {Eisenbrand, Friedrich and Rote, G{\"u}nter}, EDITOR = {Silverman, J.}, TITLE = {Fast reduction of ternary quadratic forms}, BOOKTITLE = {Proceedings of the 1st Conference on Lattices and Cryptography (CaLC-01)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Brown University, Providence, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2146}, YEAR = {2001}, PAGES = {99--111}, } @INPROCEEDINGS{ERV02, AUTHOR = {Eisenbrand, Friedrich and Rinaldi, Giovanni and Ventura, Paolo}, TITLE = {0/1 Optimization and 0/1 Primal Separation are Equivalent}, BOOKTITLE = {Proceedings of the 13th Annual ACM SIAM Symposium on Discrete Algorithms}, TYPE = {Extended Abstract}, PADDRESS = {New York, Philadelphia, USA}, ADDRESS = {San Francisco, USA}, PUBLISHER = {ACM SIAM}, MONTH = {January}, YEAR = {2002}, PAGES = {920--926}, } @INPROCEEDINGS{EsparzaPodelskiPOPL00, AUTHOR = {Esparza, Javier and Podelski, Andreas}, TITLE = {Efficient Algorithms for Pre$^\star$ and Post$^\star$ on Interprocedural Parallel Flow Graphs}, BOOKTITLE = {Proceedings of the 27th ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages (POPL-00)}, ORGANIZATION = {ACM}, PADDRESS = {New York, USA}, ADDRESS = {Boston, Massachusetts, USA}, PUBLISHER = {ACM}, MONTH = {January}, ISBN = {1-58113-125-9}, YEAR = {2000}, PAGES = {1--11}, } @INPROCEEDINGS{Fehrer93a, AUTHOR = {Fehrer, Detlef}, EDITOR = {Clarke, M. and Kruse, R. and Moral, S.}, TITLE = {A Unifying Framework for Reason Maintenance}, BOOKTITLE = {Symbolic and Quantitative Approaches to Reasoning and Uncertainty: Proceedings European Conference ECSQARU '93}, PADDRESS = {Berlin, Germany}, ADDRESS = {Granada, Spain}, PUBLISHER = {Springer}, MONTH = {August}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {747}, YEAR = {1993}, PAGES = {113--120}, NOTE = {Also appeared in Medlar {II} Report {PPR2}}, ABSTRACT = {We present a way to semantically describe reason maintenance systems, based on Gabbay's labelled deductive system idea. Our approach works for justification based as well as for assumption based methods, thus giving a {\em unifying} semantics to both of them. Instead of restricting ourselves to only propositional Horn clauses, we'll admit arbitrary logics, e.g. full first order language. This enables us to characterize systems as a whole, including both the reason maintenance component and the problem solver, nevertheless maintaining a separation between the basic logic and the part that describes the label propagation. Further we give some hints at how to implement a system based on our labelled logic and plead for what we call ``incremental calculi''.}, } @INPROCEEDINGS{Fehrer94a, AUTHOR = {Fehrer, Detlef}, EDITOR = {Cunningham, Jim and Pitt, Jeremy}, TITLE = {A Unifying Logical Framework for Reason Maintenance (Deliverable {DI.1.2-3P})}, BOOKTITLE = {Medlar {II} Report {PPR2}}, ORGANIZATION = {Department of Computing, Imperial College of Science, Technology \& Medicine}, MONTH = {July}, VOLUME = {1}, YEAR = {1994}, PAGES = {47--55}, } @PHDTHESIS{FehrerDiss1995, AUTHOR = {Fehrer, Detlef}, TITLE = {A unifying logical framework for reason maintenance}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, YEAR = {1995}, } @INPROCEEDINGS{Fehreretal94a, AUTHOR = {Fehrer, Detlef and Hustadt, Ullrich and Jaeger, Manfred and Nonnengart, Andreas and Ohlbach, Hans J{\"u}rgen and Schmidt, Renate A. and Weidenbach, Christoph and Weydert, Emil}, EDITOR = {Baader, Franz and Lenzerini, Maurizio and Nutt, Werner and Patel-Schneider, Peter F.}, TITLE = {Description Logics for Natural Language Processing}, BOOKTITLE = {International Workshop on Description Logics '94}, PADDRESS = {Saarbr{\"u}cken, Germany}, ADDRESS = {Bonn, Germany}, PUBLISHER = {DFKI}, SERIES = {Document}, VOLUME = {D-94-10}, YEAR = {1994}, PAGES = {80--84}, ABSTRACT = {In this paper we focus on the application of description logics to natural language processing. In cooperation with the {\sc pracma} project we have been developing a suitably extended knowledge representation system, called {\sc motel}. In our approach to agent modelling and natural language processing we use an extension of the well-known description language $\cal ALC$. Our system {\sc motel}\ serves on one hand as a knowledge base for the natural language front-end, and on the other hand, it provides powerful {\em logical\/} representation and reasoning components. As our approach is logic based we hope that this enhances the overall capabilities of the natural language processing (NLP) system. We present a brief overview of {\sc motel} and the different extensions we are working on, i.e.\ modal extension of description logics, a cardinality-based approach to quantitative information, reason maintenance, probablistic, non-monotonic, and abductive reasoning.}, } @INPROCEEDINGS{firozabadhi:ecai98, AUTHOR = {Firozabadhi, Babak Sadighi and van der Torre, Leendert W. N.}, EDITOR = {Prade, Henri}, TITLE = {Towards a formal analysis of control systems}, BOOKTITLE = {Proceedings of the 13th European Conference on Artificial Intelligence (ECAI-98)}, PADDRESS = {Chichester, USA}, ADDRESS = {Brighton, England}, PUBLISHER = {Wiley}, ISBN = {0-471-98431-0}, YEAR = {1998}, PAGES = {317--318}, ABSTRACT = {Formal models of electronic commerce represent and reason about security policies, for example for fraud detection and prevention. In this paper we propose a multi-layered formal model of information systems, that consists of a core system and several layers of control systems. The policies in these layers are formalized by obligations and actions of the involved parties. The formal models can be used for designing and analysing detective and preventative control systems. }, } @ARTICLE{fischm00a, AUTHOR = {Rahman, Shahid and R{\"u}ckert, Helge and Fischmann, Matthias}, JOURNAL = {Logique et Analyse}, TITLE = {Dialogues and Ontology, the Dialogical Approach to Free Logic}, VOLUME = {160}, YEAR = {1997}, PAGES = {357--374}, } @MASTERSTHESIS{Fischmann-Diplom99, AUTHOR = {Fischmann, Matthias}, TITLE = {{On Applications of Decidable Object-Oriented Type Theory}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1999}, } @ARTICLE{FrankBasin-98, AUTHOR = {Frank, Ian and Basin, David A.}, JOURNAL = {Artificial Intelligence}, TITLE = {Search in Games with Incomplete Information: A Case Study Using Bridge Card Play}, INSTITUTION = {Department of Artificial Intelligence}, TYPE = {Research Paper}, NUMBER = {1/2}, VOLUME = {100}, YEAR = {1998}, PAGES = {87--123}, NOTE = {Also available as Research Paper}, ABSTRACT = {We examine search algorithms in games with incomplete information, formalising a best defence model of such games based on the assumptions typically made when incomplete information problems are analysed in expert texts. We show that equilibrium point strategies for optimal play exist for this model, and define an algorithm capable of computing such strategies. Using this algorithm as a reference we then analyse search architectures that have been proposed for the incomplete information game of Bridge. These architectures select strategies by analysing some statistically significant collection of complete information sub-games. Our model allows us to clearly state the limitations of such architectures in producing expert analysis, and to precisely formalise and distinguish the problems that lead to sub-optimality. We illustrate these problems with simple game trees and with actual play situations from Bridge itself.}, } @INPROCEEDINGS{FrankBasinBundy92a, AUTHOR = {Frank, Ian and Basin, David A. and Bundy, Alan}, EDITOR = {Neuman, B. and Horn, W.}, TITLE = {Finesse: An Adaptation of Proof-Planning to Declarer Play in Bridge}, BOOKTITLE = {Proceedings of the 10th European Conference on Artificial Intelligence ({ECAI}-92)}, PADDRESS = {New York, USA}, ADDRESS = {Vienna, Austria}, PUBLISHER = {Wiley}, YEAR = {1992}, PAGES = {72--76}, ABSTRACT = {We present FINESSE, a system that forms optimal plans for declarer play in the game of Bridge. FINESSE adapts the technique of proof-planning, developed at Edinburgh University in the context of mathematical theorem-proving, to deal with the disjunctive choice encountered when planning under uncertainty, and the context-dependency of actions produced by the presence of an opposition. FINESSE not only demonstrated how the idea of proof-planning could be generalised, but also proved to be a very capable bridge system. In its domain of planning for individual suits, it correctly identified the proper lines of play found in many examples from the Bridge literature, supporting its decisions with probabilistic and qualitative information. Caes were even discovered in which FINESSE revealed errors in the analyses presented by recognized authorities.}, } @ARTICLE{Freiheit2005, AUTHOR = {Freiheit, J{\"o}rn and Luuk, Marc and M{\"u}nch, Susanne and Sijanski, Grozdana and Zangl, Fabrice}, JOURNAL = {Digital Evidence Journal}, TITLE = {Lexecute: Visualisation and representation of legal procedures}, ADDRESS = {Bedfordshire, UK}, NUMBER = {1}, PUBLISHER = {Pario Communications Limited}, MONTH = {May}, VOLUME = {3}, ISBN = {1750-7200}, YEAR = {2006}, PAGES = {17--27}, } @INPROCEEDINGS{Freiheit2005a, AUTHOR = {Yuan, Cong and Billington, Jonathan and Freiheit, J{\"o}rn}, TITLE = {An Abstract Model of Routing in Mobile Ad Hoc Networks}, BOOKTITLE = {Sixth Workshop and Tutorial on Practical Use of Coloured Petri Nets and the CPN Tools}, PADDRESS = {Aarhus, Denmark}, ADDRESS = {Aarhus, Denmark}, PUBLISHER = {DAIMI}, MONTH = {October}, YEAR = {2005}, PAGES = {137--156}, } @INPROCEEDINGS{Freiheit2005b, AUTHOR = {Freiheit, J{\"o}rn and M{\"u}nch, Susanne and Sch{\"o}ttle, Hendrik and Sijanski, Grozdana and Zangl, Fabrice}, EDITOR = {Meersman, Robert and Tari, Zahir and Herrero, Pilar and M{\'e}ndez, Gonzalo and Cavedon, Lawrence and Martin, David and Hinze, Annika and Buchanan, George and P{\'e}rez, Mar{\'i}a S. and Robles, V{\'i}ctor and Humble, Jan and Albani, Antonia and Dietz, Jan L.G. and Panetto, Herve and Scannapieco, Monica and Halpin, Terry and Spyns, Peter and Zaha, Johannes Maria and Zim{\'a}ny, Esteban and Stefanakis, Emmanuel and Dillon, Tharam and Feng, Ling and Jarrar, Mustafa and Lehmann, Jos and de Moor, Aldo and Duval, Erik and Aroyo, Lora}, TITLE = {Enhanced Workflow Models as a Tool for Judicial Practitioners}, BOOKTITLE = {On the move to meaningful internet systems 2005: OTM 2005 Workshops : OTM Confederated International Workshops and Posters, AWeSOMe, CAMS, GADA, MIOS+INTEROP, ORM, PhDS, SeBGIS, SWWS, and WOSE 2005}, TYPE = {Poster}, PADDRESS = {Berlin, Germany}, ADDRESS = {Agia Napa, Cyprus}, PUBLISHER = {Springer}, MONTH = {October}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3762}, ISBN = {3-540-29739-1}, YEAR = {2005}, PAGES = {26--27}, ABSTRACT = {In the past, attempts were made to make law and justice more accessible to general audience and to legal practitioners using models of legal texts. We present a new approach to make the judicial workflows easier to understand. By using process modelling methods, the developed representation emphasises on improving transparency, on promoting mutual trust and on formalising models for verification. To design semi-formal models interviews are used as well as legal texts are consulted. These models are formalised in a second step. The models are enhanced with hierarchies, modules and the generation of different views. Language problems are also treated. The subsequent formalised models are used to verify trigger events and timing of judicial workflows, which have very specific requirements in terms of periods of time and fixed dates. A new tool, Lexecute, is presented which gives new perspectives into justice and reveal new potentials for modelling methods in the field of justice.}, } @INPROCEEDINGS{Freiheit2005c, AUTHOR = {Lilith, Nimrod and Billington, Jonathan and Freiheit, J{\"o}rn}, TITLE = {Approximate Closed-Form Aggregation of a Fork-Join Structure in Generalised Stochastic Petri Nets}, BOOKTITLE = {1st International Conference on Performance Evaluation Methodologies and Tools}, PADDRESS = {New York, USA}, ADDRESS = {Pisa, Italy}, PUBLISHER = {ACM}, YEAR = {2006}, } @INPROCEEDINGS{Freiheit2005d, AUTHOR = {Simon, Carlo and Freiheit, J{\"o}rn and Olbrich, Sebastian}, EDITOR = {N{\"u}ttgens, Markus and Rump, Frank J. and Mendling, Jan}, TITLE = {Using BPEL processes defined by Event-driven Process Chains}, BOOKTITLE = {5. GI-Workshop "EPK 2006 - Gesch{\"a}ftsprozessmanagement mit Ereignisgesteuerten Prozessketten"}, PADDRESS = {Aachen, Germany}, ADDRESS = {Vienna, Austria}, PUBLISHER = {CEUR Workshop Proceedings}, YEAR = {2006}, PAGES = {121--135}, } @INPROCEEDINGS{Freiheit2005e, AUTHOR = {Freiheit, J{\"o}rn and Zangl, Fabrice}, EDITOR = {Remenyi, Dan}, TITLE = {Model-based user-interface management for public services}, BOOKTITLE = {6th European Conference on e-Government}, PADDRESS = {Reading, UK}, ADDRESS = {Marburg, Germany}, PUBLISHER = {Academic Conferences Limited}, MONTH = {April}, ISBN = {1-905305-19-2cd}, YEAR = {2006}, PAGES = {141--151}, } @INPROCEEDINGS{Freiheit2005EPK, AUTHOR = {Cuntz, Nicolas and Freiheit, J{\"o}rn and Kindler, Ekkart}, EDITOR = {Nuettgens, Markus and Rump, Frank J.}, TITLE = {{On the semantics of {EPCs: F}aster calculation for {EPCs} with small state spaces}}, BOOKTITLE = {EPK 2005 : Gesch{\"a}ftsprozessmanagement mit Ereignisgesteuerten Prozessketten}, ORGANIZATION = {SAP AG}, PADDRESS = {Bonn, Germany}, ADDRESS = {Hamburg, Germany}, PUBLISHER = {Gesellschaft f{\"u}r Informatik}, YEAR = {2005}, PAGES = {7--23}, } @MASTERSTHESIS{Friedrich-Diplom98, AUTHOR = {Friedrich, Stefan}, TITLE = {Integration of a Decision Procedure for Second-Order Monadic Logic in a Higher-Order Logic Theorem Proving Environment}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {April}, YEAR = {1998}, } @INPROCEEDINGS{Furbach:etal:OptimizingXPathDL:INAP:2004, AUTHOR = {Baumgartner, Peter and Furbach, Ulrich and Gross-Hardt, Margret and Kleemann, Thomas}, EDITOR = {Seipel, Dietmar and Hanus, Michael and Geske, Ulrich and Bartenstein, Oskar}, TITLE = {{O}ptimizing the {E}valuation of {XPath} {U}sing {D}escription {L}ogics}, BOOKTITLE = {Applications of Declarative Programming and Knowledge Management: 15th International Conference on Applications of Declarative Programming and Knowledge Management, INAP 2004, and 18th Workshop on Logic Programming, WLP 2004}, PADDRESS = {Berlin, Germany}, ADDRESS = {Potsdam, Germany}, PUBLISHER = {Springer}, MONTH = {January}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {3392}, ISBN = {0302-9743}, YEAR = {2005}, PAGES = {1--15}, ABSTRACT = {The growing use of XML in commercial as well as non-commercial domains to transport information poses new challenges to concepts to access this information. Common ways to access parts of a document use XPath-expressions. We provide a transformation of DTDs into a knowledge base in Description Logic. We use reasoning capabilities grounded in description logics to decide if a given XPath can be satisfied by a document, and to guide the search of XML-Processors into possibly successful branches of the document, thus avoiding parts of the document that will not yield results. The extension towards object oriented subclassing schemes opens this approach towards OODB-queries. In contrast to other approaches we do not use any kind of graph representing the document structure, and no steps towards incorporation of the XML/OODB-processor itself will be taken.}, } @INPROCEEDINGS{GabbayOhlbach92b, AUTHOR = {Gabbay, Dov M. and Ohlbach, Hans J{\"u}rgen}, EDITOR = {Broda, K.}, TITLE = {From a {H}ilbert Calculus to its Model Theoretic Semantics}, BOOKTITLE = {Proc.~4th Annual UK Conference on Logic Programming (APULK '92)}, PADDRESS = {Berlin, Germany}, ADDRESS = {London, UK}, PUBLISHER = {Springer}, SERIES = {Springer Workshops in Computing Series}, YEAR = {1992}, PAGES = {218--252}, ABSTRACT = {There are different ways of constructing a logic. One possibility is to define a Hilbert calculus, i.e. a kind of grammar that produces all formulae to be considered true. A logic can also be defined by a model theoretic semantics for the logical connectives in the language. In this paper a general theory is presented for the transition from a Hilbert calculus to its model theoretic semantics such that soundness and completeness are automatically guaranteed. For a given Hilbert calculus we start with a general neighbourhood semantics for n-place connectives. This semantics does not impose any built-in properties. A quantifier elimination algorithm is used to translate Hilbert axioms and rules into corresponding semantic properties. By proving certain key lemmas from these semantic properties, neighbourhood semantics can be systematically strengthened up to a version of the semantics which has as many Hilbert axioms built in as possible. The work is still incomplete and will be continued.}, } @ARTICLE{GabbayOhlbach92c, AUTHOR = {Gabbay, Dov M. and Ohlbach, Hans J{\"u}rgen}, JOURNAL = {South African Computer Journal}, TITLE = {Quantifier Elimination in Second-Order Predicate Logic}, VOLUME = {7}, YEAR = {1992}, PAGES = {35--43}, NOTE = {Also appeared in Proc.~3rd Intern.~Conference on Principles of Knowledge Representation and Reasoning, editors: B. Nebel, C. Rich and W. Swartout, pp.~425-435, Morgan Kaufmann, 1992. Also available as Research Report MPI-I-92-213}, ABSTRACT = {An algorithm is presented which eliminates second-order quantifiers over predicate variables in formulae of type $\exists P_1, \ldots, P_n \psi$ where $\psi$ is an arbitrary formula of first-order predicate logic. The resulting formula is equivalent to the original formula - if the algorithm terminates. The algorithm can for example be applied to do interpolation, to eliminate the second-order quantifiers in circumscription, to compute the correlations between structures and power structures, to compute semantic properties corresponding to Hilbert axioms in non classical logics and to compute model theoretic semantics for new logics.}, } @INPROCEEDINGS{GabbayOhlbach92cKR, AUTHOR = {Gabbay, Dov M. and Ohlbach, Hans J{\"u}rgen}, EDITOR = {Nebel, Bernhard Nebel and Rich, Charles and Swartout, William}, JOURNAL = {South African Computer Journal}, TITLE = {Quantifier Elimination in Second-Order Predicate Logic}, BOOKTITLE = {Principles of Knowledge Representation and Reasoning (KR92),}, ADDRESS = {-}, PUBLISHER = {Morgan Kaufmann}, VOLUME = {7}, YEAR = {1992}, PAGES = {425--435}, NOTE = {Also available as Research Report MPI-I-92-213}, ABSTRACT = {An algorithm is presented which eliminates second-order quantifiers over predicate variables in formulae of type $\exists P_1, \ldots, P_n \psi$ where $\psi$ is an arbitrary formula of first-order predicate logic. The resulting formula is equivalent to the original formula - if the algorithm terminates. The algorithm can for example be applied to do interpolation, to eliminate the second-order quantifiers in circumscription, to compute the correlations between structures and power structures, to compute semantic properties corresponding to Hilbert axioms in non classical logics and to compute model theoretic semantics for new logics.}, } @MASTERSTHESIS{Gaede95-Mastersthesis, AUTHOR = {Gaede, Bernd}, TITLE = {Superposition Extended with Sorts}, SCHOOL = {Universit{\"a}t Kaiserslautern}, TYPE = {Master's thesis}, MONTH = {July}, YEAR = {1995}, ABSTRACT = {Sorted problem formulations often result in shorter proofs. In this thesis, the integration of ordered inference rules and rules for sort constraints in one calculus and the resulting system architecture for its implementation SPASS are presented. Thus, SPASS (Synergetic Prover Augmenting Superposition with Sorted logic) is a theorem-proving program for first-order logic with equality and sorts.}, } @INPROCEEDINGS{GaillourdetHillenbrandLoechner2003, AUTHOR = {Gaillourdet, Jean-Marie and Hillenbrand, Thomas and L{\"o}chner, Bernd and Spies, Hendrik}, EDITOR = {Baader, Franz}, TITLE = {The New {WALDMEISTER} Loop at Work}, BOOKTITLE = {Automated deduction, CADE-19 : 19th International Conference on Automated Deduction}, PADDRESS = {Berlin, Germany}, ADDRESS = {Miami, Florida}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2741}, YEAR = {2003}, PAGES = {317--321}, ABSTRACT = {We present recent developments within the theorem prover \textsc{Waldmeister}. They rely on a novel organization of the underlying saturation-based proof procedure into a system architecture. As is known, the saturation process tends to quickly fill the memory available unless preventive measures are employed. To overcome this problem, our new ``\textsc{Waldmeister} loop'' features a highly compact representation of the search state, exploiting its inherent structure. The implementation just being available, the cost and the benefits of the concept now can exactly be measured. Indeed are our expectations met concerning the drastic cut-down of memory usage with only moderate overhead of time. In addition it has turned out that the revealed structure of the search state paves the way to an easily implemented parallelization of the prover with modest communication requirements and rewarding speed-ups. In order to minimize communication-related latencies, we discuss some variations of the loop to maximally profit from multiple processors.}, } @PHDTHESIS{Gamkrelidze-Thesis-2001, AUTHOR = {Gamkrelidze, Alexander}, TITLE = {{Einige Optimierungsmethoden hierarchischer Schaltkreise}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {December}, YEAR = {2001}, } @INPROCEEDINGS{GanHNOT-CAV-04, AUTHOR = {Ganzinger, Harald and Hagen, George and Nieuwenhuis, Robert and Oliveras, Albert and Tinelli, Cesare}, EDITOR = {Alur, Rajeev and Peled, Doron}, TITLE = {{DPLL(T)}: Fast Decision Procedures}, BOOKTITLE = {Computer aided verification : 16th International Conference, CAV 2004}, PADDRESS = {Berlin, Germany}, ADDRESS = {Boston, Massachusetts}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3114}, ISBN = {3-540-22342-8}, YEAR = {2004}, PAGES = {175--188}, } @INPROCEEDINGS{GanKor:ThInst:2006, AUTHOR = {Ganzinger, Harald and Korovin, Konstantin}, EDITOR = {Hermann, Miki and Voronkov, Andrei}, TITLE = {Theory Instantiation}, BOOKTITLE = {13th Conference on Logic for Programming Artificial Intelligence Reasoning (LPAR'06)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Phnom Penh, Cambodia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {4246}, ISBN = {3-540-4828-4}, YEAR = {2006}, PAGES = {497--511}, ABSTRACT = {In this paper we present a method of integrating theory reasoning into the instantiation framework. One of the distinctive features of our approach is that it allows us to employ off-the-shelf satisfiability solvers for ground clauses modulo theories, as a part of general first-order reasoning. As an application of this approach, we show how it is possible to combine the instantiation calculus with other calculi, such as ordered resolution and paramodulation.}, } @INPROCEEDINGS{Ganzinger-01-lics, AUTHOR = {Ganzinger, Harald}, EDITOR = {Williams, Denise A.}, TITLE = {Relating Semantic and Proof-Theoretic Concepts for Polynomial Time Decidability of Uniform Word Problems}, BOOKTITLE = {Proceedings of the 16th IEEE Symposium on Logic in Computer Science (LICS-01)}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Boston, USA}, PUBLISHER = {IEEE}, ISBN = {0-7695-1281-x}, YEAR = {2001}, PAGES = {81--90}, ABSTRACT = {In this paper we compare three approaches to polynomial time decidability for uniform word problems for quasi-varieties. Two of the approaches, by Evans and Burris, respectively, are semantical, referring to certain embeddability and axiomatizability properties. The third approach is proof-theoretic in nature, inspired by McAllester's concept of local inference. We define two closely related notions of locality for equational Horn theories and show that both the criteria by Evans and Burris lie in between these two concepts. In particular, our notion of weak locality subsumes both Evans' and Burris' method.}, } @INPROCEEDINGS{Ganzinger-02-cade, AUTHOR = {Ganzinger, Harald}, EDITOR = {Voronkov, Andrei}, TITLE = {Shostak Light}, BOOKTITLE = {Automated deduction, CADE-18 : 18th International Conference on Automated Deduction}, PADDRESS = {Heidelberg, Germany}, ADDRESS = {Copenhagen, Denmark}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2392}, ISBN = {3-540-43931-5}, YEAR = {2002}, PAGES = {332--346}, ABSTRACT = {We represent the essential ingredients of Shostak's procedure at a high level of abstraction, and as a refinement of the Nelson-Oppen procedure. We analyze completeness issues of the method based on a general notion of theories. We also formalize a notion of sigma-models and show that on the basis of Shostak's procedure we cannot distinguish a theory from its approximation represented by the class of its sigma-models.}, } @ARTICLE{Ganzinger-91-jsc, AUTHOR = {Ganzinger, Harald}, JOURNAL = {Journal of Symbolic Computation}, TITLE = {A completion procedure for conditional equations}, VOLUME = {11}, YEAR = {1991}, PAGES = {51--81}, ABSTRACT = {The paper presents a new completion procedure for conditional equations. The work is based on the notion of reductive conditional rewriting and the procedure has been designed to in particular handle nonreductive equations that are generated during completion. The paper also describes techniques for simplification of conditional equations and rules, so that the procedure terminates on more specifications. The correctness proofs which form a substantial part of this paper employ recursive path orderings on the proof trees of conditional equational logic, an extension of the ideas of Bachmair, Dershowitz and Hsiang to the conditional case.}, } @ARTICLE{Ganzinger-91-tcs, AUTHOR = {Ganzinger, Harald}, JOURNAL = {Theoretical Computer Science}, TITLE = {Order-Sorted Completion: The Many-Sorted Way}, PUBLISHER = {North-Holland Publishing Co.}, VOLUME = {89}, ISBN = {0304-3975}, YEAR = {1991}, PAGES = {3--32}, ABSTRACT = {Order-sorted specifications can be transformed into equivalent many-sorted ones by using injections to implement subsort relations. In this paper we improve previous results % of Goguen, Jouannaud, and Meseguer about the relation between order-sorted and many-sorted rewriting. We then apply techniques for the completion of many-sorted conditional equations to systems obtained from translating order-sorted conditional equations. Emphasis will be on ways to overcome some of the problems with non-sort-decreasing rules.}, } @UNPUBLISHED{Ganzinger-94-sat, AUTHOR = {Ganzinger, Harald}, TITLE = {The {Saturate} System}, YEAR = {1994}, NOTE = {Available on the World-Wide Web and URL http://www.mpi-sb.mpg.de/SATURATE/Saturate.html}, ABSTRACT = {The Saturate system is an experimental theorem prover based on saturation. It has originally been developed as an implementation of the superposition calculus by Pilar Nivela and Robert Nieuwenhuis from the Technical University of Catalonia, Barcelona. The version the use of which is described in this document now contains extensions by chaining techniques for arbitrary transitive relations implemented by Harald Ganzinger, MPI Informatik, Saarbr\"ucken, with the help of Robert Nieuwenhuis.}, } @PROCEEDINGS{Ganzinger-ed-cade-1999, EDITOR = {Ganzinger, Harald}, TITLE = {Proceedings of the 16th International Conference on Automated Deduction (CADE-16)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Trento, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1632}, ISBN = {3-540-66222-7}, YEAR = {1999}, PAGES = {443}, ABSTRACT = {In this paper we give a method for automated theorem proving in the universal theory of certain varieties of distributive lattices with well-behaved operators. For this purpose, we use extensions of Priestley's representation theorem for distributive lattices. We first establish a link between satisfiability of universal sentences with respect to varieties of distributive lattices with operators and satisfiability with respect to certain classes of relational structures. We then use these results for giving a method for translation to clause form of universal sentences in such varieties, and obtain decidability and complexity results for the universal theory of some such varieties. The advantage is that we avoid the explicit use of the full algebraic structure of such lattices, instead using sets endowed with a reflexive and transitive relation and with additional functions and relations. We first studied this type of relationships in the context of finitely-valued logics and then extended the ideas to more general non-classical logics. This paper shows that the idea is much more general. In particular, the method presented here subsumes both existing methods for translating modal logics to classical logic and methods for automated theorem proving in finitely-valued logics based on distributive lattices with operators. }, } @INCOLLECTION{Ganzinger-et-al-00-AIML, AUTHOR = {Ganzinger, Harald and Hustadt, Ullrich and Meyer, Christoph and Schmidt, Renate A.}, EDITOR = {Zakharyaschev, Michael and Segerberg, Krister and de Rijke, Maarten and Wansing, Heinrich}, TITLE = {A Resolution-Based Decision Procedure for Extensions of {K}4}, BOOKTITLE = {Advances in Modal Logic, Volume 2}, CHAPTER = {9}, ADDRESS = {Stanford, USA}, PUBLISHER = {CSLI}, SERIES = {CSLI Lecture Notes}, VOLUME = {119}, ISBN = {1-57586-272-7}, YEAR = {2001}, PAGES = {225--246}, ABSTRACT = {This paper presents a resolution decision procedure for transitive propositional modal logics. The procedure combines the relational translation method with an ordered chaining calculus designed to avoid unnecessary inferences with transitive relations. We show the logics K4, KD4 and S4 can be transformed into a bounded class of well-structured clauses closed under ordered resolution and negative chaining.}, } @PROCEEDINGS{Ganzinger-et-al-01-Dagstuhl, EDITOR = {Furbach, Ulrich and Ganzinger, Harald and Hasegawa, Ryuzo and Kapur, Deepak}, TITLE = {Deduction}, INSTITUTION = {Internationales Begegnungs- und Forschungszentrum f{\"u}r Informatik }, TYPE = {Dagstuhl-Seminar-Report}, PADDRESS = {Wadern, Germany}, ADDRESS = {Wadern/Dagstuhl, Germany}, NUMBER = {232}, PUBLISHER = {IBFI}, SERIES = {Dagstuhl-Seminar-Report}, ISBN = {0940-1121}, YEAR = {2000}, PAGES = {24}, } @INPROCEEDINGS{Ganzinger-SofronieStokkermans-Waldmann-ijcar-2004, AUTHOR = {Ganzinger, Harald and Sofronie-Stokkermans, Viorica and Waldmann, Uwe}, EDITOR = {Basin, David and Rusinowitch, Michael}, TITLE = {Modular Proof Systems for Partial Functions with Weak Equality}, BOOKTITLE = {Automated reasoning : Second International Joint Conference, IJCAR 2004}, PADDRESS = {Berlin}, ADDRESS = {Cork, Ireland}, PUBLISHER = {Springer}, MONTH = {June}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {3097}, ISBN = {3-540-22345-2}, YEAR = {2004}, PAGES = {168--182}, ABSTRACT = {The paper presents a modular superposition calculus for the combination of first-order theories involving both total and partial functions. Modularity means that inferences are pure, only involving clauses over the alphabet of either one, but not both, of the theories. The calculus is shown to be complete provided that functions that are not in the intersection of the component signatures are declared as partial. This result also means that if the unsatisfiability of a goal modulo the combined theory does not depend on the totality of the functions in the extensions, the inconsistency will be effectively found. Moreover, we consider a constraint superposition calculus for the case of hierarchical theories and show that it has a related modularity property. Finally we identify cases where the partial models can always be made total so that modular superposition is also complete with respect to the standard (total function) semantics of the theories.}, } @ARTICLE{Ganzinger-Stuber-ic-05, AUTHOR = {Ganzinger, Harald and Stuber, J{\"u}rgen}, JOURNAL = {Information and Computation}, TITLE = {Superposition with equivalence reasoning and delayed clause normal form transformation}, ADDRESS = {Amsterdam, The Netherlands}, NUMBER = {1-2}, PUBLISHER = {Elsevier}, VOLUME = {199}, YEAR = {2005}, PAGES = {3--23}, ABSTRACT = {This paper describes a superposition calculus where quantifiers are eliminated lazily. Superposition and simplification inferences may employ equivalences that have arbitrary formulas at their smaller side. A closely related calculus is implemented in the Saturate system and has shown useful on many examples, in particular in set theory. The paper presents a completeness proof and reports on practical experience obtained with the Saturate system.}, } @PROCEEDINGS{Ganzinger1999LPAR, EDITOR = {Ganzinger, Harald and McAllester, David and Voronkov, Andrei}, TITLE = {Proceedings of the 6th International Conference on Logic for Programming and Automated Reasoning (LPAR-99)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Tbilisi, Georgia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1705}, ISBN = {3-540-66492-0}, YEAR = {1999}, PAGES = {397}, NOTE = {Earlier version: Technical Report MPI-I-1999-2-003, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken}, ABSTRACT = {In divisible torsion-free abelian groups, the efficiency of the cancellative superposition calculus can be greatly increased by combining it with a variable elimination algorithm that transforms every clause into an equivalent clause without unshielded variables. We show that the resulting calculus is not only refutationally complete (even in the presence of arbitrary free function symbols), but that it is also a decision procedure for the theory of divisible torsion-free abelian groups.}, } @INPROCEEDINGS{Ganzinger2003a, AUTHOR = {Ganzinger, Harald}, EDITOR = {Danvy, Olivier and Filinski, Andrzej}, TITLE = {Bottom-Up Deduction with Deletion and Priorities}, BOOKTITLE = {Programs as Data Objects (PADO-01) : Second Symposium PADO 2001}, PADDRESS = {Berlin, Germany}, ADDRESS = {Aarhus, Denmark}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2053}, ISBN = {0302-9743}, YEAR = {2001}, PAGES = {276--277}, } @INPROCEEDINGS{Ganzinger96-ICALP-23, AUTHOR = {Ganzinger, Harald}, EDITOR = {Meyer auf der Heide, Friedhelm and Monien, Burkhard}, TITLE = {Saturation-based theorem proving (abstract)}, BOOKTITLE = {Automata, Languages and Programming: International Colloquium (ICALP-23)}, TYPE = {abstract}, PADDRESS = {Berlin, Germany}, ADDRESS = {Paderborn, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1099}, ISBN = {3540614400}, YEAR = {1996}, PAGES = {1--3}, } @ARTICLE{Ganzinger98, AUTHOR = {Ganzinger, Harald}, JOURNAL = {Theoretical Computer Science}, TITLE = {Preface}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {1/2}, PUBLISHER = {Elsevier}, MONTH = {November}, VOLUME = {208}, ISBN = {0304-3975}, YEAR = {1998}, PAGES = {1}, } @INPROCEEDINGS{GanzingerHillenbrandWaldmann2003, AUTHOR = {Ganzinger, Harald and Hillenbrand, Thomas and Waldmann, Uwe}, EDITOR = {Baader, Franz}, TITLE = {Superposition modulo a {Shostak} Theory}, BOOKTITLE = {Automated Deduction, CADE-19 : 19th International Conference on Automated Deduction}, PADDRESS = {Berlin, Germany}, ADDRESS = {Miami, Florida}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2741}, ISBN = {3-540-40559-3}, YEAR = {2003}, PAGES = {182--196}, ABSTRACT = { We investigate superposition modulo a Shostak theory $T$ in order to facilitate reasoning in the amalgamation of $T$ and a free theory~$F$. % Free operators occur naturally e.\,g.\ in program verification problems when abstracting over subroutines. If their behaviour in addition can be specified axiomatically, much more of the program semantics can be captured. % Combining the Shostak-style components for deciding the clausal validity problem with the ordering and saturation techniques developed for equational reasoning, we derive a refutationally complete calculus on mixed ground clauses which result for example from CNF transforming arbitrary universally quantified formulae. % The calculus works modulo a Shostak theory in the sense that it operates on canonizer normalforms. For the Shostak solvers that we study, coherence comes for free: no coherence pairs need to be considered.}, } @ARTICLE{GanzingerJacquemardVeanes-00-ijfcs, AUTHOR = {Ganzinger, Harald and Jacquemard, Florent and Veanes, Margus}, JOURNAL = {International Journal of Foundations of Computer Science}, TITLE = {Rigid Reachability: The Non-Symmetric Form of Rigid {E}-unification}, ADDRESS = {Singapore}, NUMBER = {1}, PUBLISHER = {World Scientific}, VOLUME = {11}, ISBN = {0129-0541}, YEAR = {2000}, PAGES = {3--27}, ABSTRACT = {We show that rigid reachability, the non-symmetric form of rigid E-unification, is already undecidable in the case of a single constraint. From this we infer the undecidability of a new and rather restricted kind of second-order unification. We also show that certain decidable subclasses of the problem which are PTIME-complete in the equational case become EXPTIME-complete when symmetry is absent. By applying automata-theoretic methods, simultaneous monadic rigid reachability with ground rules is shown to be PSPACE-complete. Moreover, we identify two decidable non-monadic fragments that are complete for EXPTIME.}, } @INPROCEEDINGS{GanzingerJacquemardVeanes-98, AUTHOR = {Ganzinger, Harald and Jacquemard, Florent and Veanes, Margus}, EDITOR = {Hsiang, Jieh and Ohori, Atsushi}, TITLE = {Rigid Reachability}, BOOKTITLE = {Proceedings of the 4th Asian Computing Science Conference on Advances in Computing Science (ASIAN-98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Manila, The Philippines,}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1538}, ISBN = {3-540-65388-0}, YEAR = {1998}, PAGES = {4--21}, NOTE = {A full version of this paper is available as MPI-I Research Report MPI-I-98-2-013.}, ABSTRACT = {We show that rigid reachability, the non-symmetric form of rigid E-unification, is undecidable already in the case of a single constraint. From this we infer the undecidability of a new rather restricted kind of second-order unification. We also show that certain decidable subclasses of the problem which are PTIME-complete in the equational case become EXPTIME-complete when symmetry is absent. By applying automata-theoretic methods, simultaneous monadic rigid reachability with ground rules is shown to be in EXPTIME.}, } @INPROCEEDINGS{GanzingerKorovin-03-lics, AUTHOR = {Ganzinger, Harald and Korovin, Konstantin}, EDITOR = {Kolaitis, Phokion}, TITLE = {New Directions in Instantiation-Based Theorem Proving}, BOOKTITLE = {18th Annual IEEE Symposium on Logic in Computer Science (LICS-03)}, ORGANIZATION = {Institute of Electrical and Electronics Engineers (IEEE)}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Ottawa, Canada}, PUBLISHER = {IEEE}, ISBN = {0-7695-1884-2}, YEAR = {2003}, PAGES = {55--64}, ABSTRACT = {We consider instantiation-based theorem proving whereby instances of clauses are generated by certain inferences, and where inconsistency is detected by propositional tests. We give a model construction proof of completeness by which restrictive inference systems as well as admissible simplification techniques can be justified. Another contribution of the paper are novel inference systems that allow one to also employ decision procedures for first-order fragments more complex than propositional logic. The decision procedure provides for an approximative consistency test, and the instance generation inference system is a means of successively refining the approximation.}, } @INPROCEEDINGS{GanzingerMcAllester-01-ijcar, AUTHOR = {Ganzinger, Harald and McAllester, David}, EDITOR = {Gor{\'e}, Rajeev and Leitsch, Alexander and Nipkow, Tobias}, TITLE = {A new meta-complexity theorem for bottom-up logic programs}, BOOKTITLE = {Automated reasoning : First International Joint Conference, IJCAR 2001}, PADDRESS = {Berlin, Germany}, ADDRESS = {Siena, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2083}, ISBN = {3-540-42254-4}, YEAR = {2001}, PAGES = {514--528}, ABSTRACT = {Nontrivial meta-complexity theorems, proved once for a programming language as a whole, facilitate the presentation and analysis of particular algorithms. This paper gives a new meta-complexity theorem for bottom-up logic programs that is both more general and more accurate than previous such theorems. The new theorem applies to algorithms not handled by previous meta-complexity theorems, greatly facilitating their analysis.}, } @INPROCEEDINGS{GanzingerMcAllester-02-iclp, AUTHOR = {Ganzinger, Harald and McAllester, David}, EDITOR = {Stuckey, Peter J.}, TITLE = {Logical Algorithms}, BOOKTITLE = {Logic Programming. 18th International Conference, ICLP 2002}, PADDRESS = {Berlin, Germany}, ADDRESS = {Copenhagen, Denmark}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2401}, ISBN = {3-540-43930-7}, YEAR = {2002}, PAGES = {209--223}, ABSTRACT = {It is widely accepted that many algorithms can be concisely and clearly expressed as logical inference rules. However, logic programming has been inappropriate for the study of the running time of algorithms because there has not been a clear and precise model of the run time of a logic program. We present a logic programming model of computation appropriate for the study of the run time of a wide variety of algorithms.}, } @INPROCEEDINGS{GanzingerMeyerVeanes-99-lics, AUTHOR = {Ganzinger, Harald and Meyer, Christoph and Veanes, Margus}, EDITOR = {Longo, Giuseppe}, TITLE = {The Two-Variable Guarded Fragment with Transitive Relations}, BOOKTITLE = {Proceedings of the 14th Annual IEEE Symposium on Logic in Computer Science (LICS-99)}, ORGANIZATION = {IEEE Computer Society}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Trento, Italy}, PUBLISHER = {IEEE}, ISBN = {0-7695-0158-3}, YEAR = {1999}, PAGES = {24--34}, ABSTRACT = {We consider the restriction of the guarded fragment to the two-variable case where, in addition, binary relations may be specified as transitive. We show that (i) this very restricted form of the guarded fragment without equality is undecidable and that (ii) when allowing transitive relations other than equality to occur only in guards, the logic becomes decidable. The latter subclass of the guarded fragment is the one that occurs naturally when translating multi-modal logics of the type K4, S4 or S5 into first-order logic. We also show that the loosely guarded fragment with a single transitive relation is undecidable.}, } @INPROCEEDINGS{GanzingerMeyerWeidenbach-97-cade, AUTHOR = {Ganzinger, Harald and Meyer, Christoph and Weidenbach, Christoph}, EDITOR = {McCune, William}, TITLE = {Soft Typing for Ordered Resolution}, BOOKTITLE = {Proceedings of the 14th International Conference on Automated Deduction (CADE-14)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Townsville, Australia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1249}, ISBN = {3-540-63104-6}, YEAR = {1997}, PAGES = {321--335}, ABSTRACT = {We propose a variant of ordered resolution with semantic restrictions based on interpretations which are identified by the given atom ordering and selection function. Techniques for effectively approximating validity in these interpretations are described that are related to methods of soft typing for programming languages. The framework is shown to be strictly more general than certain related methods. Implementation in the \spass\ prover has lead to encouraging experimental results.}, } @INPROCEEDINGS{GanzingerNieuwenhuis-01-ccl, AUTHOR = {Ganzinger, Harald and Nieuwenhuis, Robert}, EDITOR = {Comon, Hubert and March{\'e}, Claude and Treinen, Ralf}, TITLE = {Constraints and Theorem Proving}, BOOKTITLE = {Contraints in Computational Logics, International Summer School (CCL-99)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Gif-sur-Yvette, France}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2002}, ISBN = {3-540-41950-0}, YEAR = {2001}, PAGES = {159--201}, ABSTRACT = {This paper is a tutorial on methods for first-order theorem proving with constraints.}, } @INPROCEEDINGS{GanzingerNieuwenhuisNivela-01-ijcar, AUTHOR = {Ganzinger, Harald and Nieuwenhuis, Robert and Nivela, Pilar}, EDITOR = {Gor{\'e}, Rajeev and Leitsch, Alexander and Nipkow, Tobias}, TITLE = {Context trees}, BOOKTITLE = {Automated reasoning : First International Joint Conference, IJCAR 2001}, PADDRESS = {Berlin, Germany}, ADDRESS = {Siena, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2083}, ISBN = {3-540-42254-4}, YEAR = {2001}, PAGES = {242--256}, ABSTRACT = {Indexing data structures are well-known to be crucial for the efficiency of the current state-of-the-art theorem provers. Examples are \emph{discrimination trees}, which are like tries where terms are seen as strings and common prefixes are shared, and \emph{substitution trees}, where terms keep their tree structure and all common \emph{contexts} can be shared. Here we describe a new indexing data structure, \emph{context trees}, where, by means of a limited kind of context variables, also common subterms can be shared, even if they occur below different function symbols. Apart from introducing the concept, we also provide evidence for its practical value. We describe an implementation of context trees based on Curry terms and on an extension of substitution trees with equality constraints and where one does not distinguish between \emph{internal} and \emph{external} variables. Experiments with matching show that our preliminary implementation is already competitive with tightly coded current state-of-the-art implementations of the other main techniques. In particular space consumption of context trees is substantially less than for other index structures.}, } @ARTICLE{GanzingerNieuwenhuisNivela-03-jar, AUTHOR = {Ganzinger, Harald and Nieuwenhuis, Robert and Nivela, Pilar}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {Fast Term Indexing with Coded Context Trees}, ADDRESS = {Dordrecht, the Netherlands}, NUMBER = {2}, PUBLISHER = {Kluwer}, MONTH = {February}, VOLUME = {32}, YEAR = {2004}, PAGES = {103--120}, ABSTRACT = {Indexing data structures have a crucial impact on the performance of automated theorem provers. Examples are discrimination trees, which are like tries where terms are seen as strings and common prefixes are shared, and substitution trees, where terms keep their tree structure and all common contexts can be shared. Here we describe a new indexing data structure, called context trees, where, by means of a limited kind of context variables, also common subterms can be shared, even if they occur below different function symbols. Apart from introducing the concept, we also provide evidence for its practical value. We show how context trees can be implemented by means of abstract machine instructions. Experiments with matching benchmarks show that our implementation is competitive with tightly coded current state-of-the-art implementations of the other main techniques. In particular space consumption of context trees is significantly less than for other index structures.}, } @INPROCEEDINGS{GanzingerNivelle-99-lics, AUTHOR = {Ganzinger, Harald and de Nivelle, Hans}, EDITOR = {Longo, Giuseppe}, TITLE = {A Superposition Decision Procedure for the Guarded Fragment with Equality}, BOOKTITLE = {Proceedings of the 14th Annual IEEE Symposium on Logic in Computer Science (LICS-99)}, ORGANIZATION = {IEEE Computer Society}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Trento, Italy}, PUBLISHER = {IEEE}, ISBN = {0-7695-0158-3}, YEAR = {1999}, PAGES = {295--303}, ABSTRACT = {We give a decision procedure for the guarded fragment with equality. The procedure is based on resolution with superposition. The relevance of the guarded fragment lies in the fact that many modal logics can be translated into it. In this way the guarded fragment acts as a framework explaining some of the nice properties of these modal logics. By constructing an implementable decision procedure for the guarded fragments we define an effective procedure for deciding these modal logics. It is surprising to see that one does not need any sophisticated simplification and redundancy elimination method to make superposition terminate on the class of clauses that is obtained from the clausification of guarded formulas. Yet the decision procedure obtained is optimal with regard to time complexity.}, } @PROCEEDINGS{GanzingerRTA96, EDITOR = {Ganzinger, Harald}, TITLE = {Rewriting Techniques and Applications, 7th International Conference, RTA-96}, ORGANIZATION = {Center for Discrete Mathematics and Computer Science (DIMACS)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Rutgers University, New Brunswick, NJ, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1103}, ISBN = {3-540-61464-8}, YEAR = {1996}, PAGES = {435}, NOTE = {One of the conferences participating in the 1996 Federated Logic Conference (FLoC)}, } @INPROCEEDINGS{GanzingerSofronie-Stokkermans-00-ismvl, AUTHOR = {Ganzinger, Harald and Sofronie-Stokkermans, Viorica}, TITLE = {Chaining Techniques for Automated Theorem Proving in Many-Valued Logics}, BOOKTITLE = {Proceedings of the 30th IEEE International Symposium on Multiple-Valued Logic (ISMVL-00)}, ORGANIZATION = {IEEE Computer Society Technical Committee on Multiple-Valued Logic; Oregon Center for Advanced Technology Education}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Portland, Oregon}, PUBLISHER = {IEEE}, ISBN = {0-7695-0692-5}, YEAR = {2000}, PAGES = {337--344}, ABSTRACT = {We apply chaining techniques to automated theorem proving in many-valued logics. In particular, we show that superposition specializes to a refined version of the many-valued resolution rules introduced by Baaz and Ferm{\"u}ller, and that ordered chaining can be specialized to a refutationally complete inference system for regular clauses.}, } @INPROCEEDINGS{GanzingerStuber-2003-cade, AUTHOR = {Ganzinger, Harald and Stuber, J{\"u}rgen}, EDITOR = {Baader, Franz}, TITLE = {Superposition with Equivalence Reasoning and Delayed Clause Normal Form Transformation}, BOOKTITLE = {Automated Deduction, CADE-19 : 19th International Conference on Automated Deduction}, PADDRESS = {Berlin, Germany}, ADDRESS = {Miami, Florida}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2741}, ISBN = {3-540-40559-3}, YEAR = {2003}, PAGES = {335--349}, ABSTRACT = {The paper describes a superposition calculus where quantifiers are eliminated lazily. Superposition and simplification inferences may employ equivalences that have arbitrary formulas at their smaller side. A closely related calculus is implemented in the Saturate system and has shown useful on many examples, in particular in set theory. The paper presents a completeness proof and reports on practical experience obtained with the Saturate system.}, } @INCOLLECTION{GanzingerStuber-92, AUTHOR = {Ganzinger, Harald and Stuber, J{\"u}rgen}, EDITOR = {Buchmann, J. and Ganzinger, Harald and Paul, W. J.}, TITLE = {Inductive theorem proving by consistency for first-order clauses}, BOOKTITLE = {Informatik - Festschrift zum 60. Geburtstag von G{\"u}nter Hotz}, ADDRESS = {?}, PUBLISHER = {Teubner}, YEAR = {1992}, PAGES = {441--462}, NOTE = {Also in Proc.~CTRS'92, LNCS~656, pp.~226--241}, ABSTRACT = {We show how the method of proof by consistency can be extended to proving properties of the perfect model of a set of first-order clauses with equality. Technically proofs by consistency will be similar to proofs by case analysis over the term structure. As our method also allows to prove sufficient-completeness of function definitions in parallel with proving an inductive theorem we need not distinguish between constructors and defined functions. Our method is linear and refutationally complete with respect to the perfect model, it supports lemmas in a natural way, and it provides for powerful simplification and elimination techniques.}, } @INPROCEEDINGS{GanzingerWaldmann-92-ctrs, AUTHOR = {Ganzinger, Harald and Waldmann, Uwe}, EDITOR = {Rusinowitch, M. and R{\'e}my, J.-L.}, TITLE = {Termination Proofs of Well-Moded Logic Programs Via Conditional Rewrite Systems}, BOOKTITLE = {Proceedings of the 3rd International Workshop on Conditional Term Rewriting Systems '92}, PADDRESS = {Berlin, Germany}, ADDRESS = {?}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {656}, YEAR = {1992}, PAGES = {430--437}, ABSTRACT = {In this paper, it is shown that a translation from logic programs to conditional rewrite rules can be used in a straightforward way to check (semi-automatically) whether a program is terminating under the prolog selection rule.}, } @INPROCEEDINGS{GanzingerWaldmann1996CADE, AUTHOR = {Ganzinger, Harald and Waldmann, Uwe}, EDITOR = {McRobbie, Michael A. and Slaney, John K.}, TITLE = {Theorem Proving in Cancellative Abelian Monoids (Extended Abstract)}, BOOKTITLE = {Proceedings of the 13th International Conference on Automated Deduction (CADE-13)}, PADDRESS = {Berlin, Germany}, ADDRESS = {New Brunswick, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1104}, ISBN = {3-540-61511-3}, YEAR = {1996}, PAGES = {388--402}, NOTE = {Full version: Technical Report MPI-I-96-2-001, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken, Germany, January 1996.}, ABSTRACT = {Cancellative abelian monoids encompass abelian groups, but also such ubiquitous structures as the natural numbers or multisets. Both the AC axioms and the cancellation law are difficult for a general purpose theorem prover, as they create many variants of clauses which contain sums. We describe a refined superposition calculus for cancellative abelian monoids which requires neither explicit inferences with the theory clauses nor extended equations or clauses. Strong ordering constraints allow us to restrict to inferences that involve the maximal term of the maximal sum in the maximal literal. Besides, the search space is reduced drastically by variable elimination techniques.}, } @ARTICLE{Ganzinger:2001:EDM, AUTHOR = {Ganzinger, Harald}, JOURNAL = {ACM SIGPLAN Notices}, TITLE = {Efficient deductive methods for program analysis}, ADDRESS = {New York, USA}, NUMBER = {3}, PUBLISHER = {ACM}, MONTH = {March}, VOLUME = {36}, ISBN = {0362-1340}, YEAR = {2001}, PAGES = {102--103}, } @INPROCEEDINGS{GanzKor:InstEq:2004, AUTHOR = {Ganzinger, Harald and Korovin, Konstantin}, EDITOR = {Marcinkowski, Jerzy and Tarlecki, Andrzej}, TITLE = {Integration of equational reasoning into instantiation-based theorem proving}, BOOKTITLE = {Computer science logic : 18th International Workshop CSL 2004, 13th Annual Conference of the EACSL}, PADDRESS = {Berlin}, ADDRESS = {Karpacz, Poland}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3210}, ISBN = {3-540-23024-6}, YEAR = {2004}, PAGES = {71--84}, ABSTRACT = {In this paper we present a method for integrating equational reasoning into instantiation-based theorem proving. The method employs a satisfiability solver for ground equational clauses together with an instance generation process based on an ordered paramodulation type calculus for literals. The completeness of the procedure is proved using the the model generation technique, which allows us to justify redundancy elimination based on appropriate orderings.}, } @INPROCEEDINGS{GeorgievaHustadtSchmidt02b, AUTHOR = {Georgieva, Lilia and Hustadt, Ullrich and Schmidt, Renate A.}, EDITOR = {Voronkov, Andrei}, TITLE = {A New Clausal Class Decidable by Hyperresolution}, BOOKTITLE = {Automated deduction, CADE-18 : 18th International Conference on Automated Deduction}, PADDRESS = {Heidelberg, Germany}, ADDRESS = {Copenhagen, Denmark}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2392}, ISBN = {3-540-43931-5}, YEAR = {2002}, PAGES = {260--274}, ABSTRACT = {In this paper we define a new clausal class, called $\mathcal{BU}$, which can be decided by hyperresolution with splitting. We also consider the model generation problem for $\mathcal{BU}$ and show that hyperresolution plus splitting can also be used as a Herbrand model generation procedure for $\mathcal{BU}$ and, furthermore, that the addition of a local minimality test allows us to generate only minimal Herbrand models for clause sets in $\mathcal{BU}$. In addition, we investigate the relationship of $\mathcal{BU}$ to other solvable classes.}, } @TECHREPORT{GeorgievaHustadtSchmidt02c, AUTHOR = {Georgieva, Lilia and Hustadt, Ullrich and Schmidt, Renate A.}, TITLE = {A New Clausal Class Decidable by Hyperresolution}, INSTITUTION = {University of Manchester}, TYPE = {Preprint Series}, ADDRESS = {UK}, NUMBER = {CSPP-18}, MONTH = {July}, YEAR = {2002}, PAGES = {19}, NOTE = {Long version of~\cite{GeorgievaHustadtSchmidt02b}.}, ABSTRACT = {In this paper we define a new clausal class, called $\mathcal{BU}$, which can be decided by hyperresolution with splitting. We also consider the model generation problem for $\mathcal{BU}$ and show that hyperresolution plus splitting can also be used as a Herbrand model generation procedure for $\mathcal{BU}$ and, furthermore, that the addition of a local minimality test allows us to generate only minimal Herbrand models for clause sets in $\mathcal{BU}$. In addition, we investigate the relationship of $\mathcal{BU}$ to other solvable classes.}, } @INPROCEEDINGS{GeorgievaHustadtSchmidt02d, AUTHOR = {Georgieva, Lilia and Hustadt, Ullrich and Schmidt, Renate A.}, EDITOR = {Horrocks, Ian and Tessaris, Sergio}, TITLE = {On the Relationship Between Decidable Fragments, Non-Classical Logics, and Description Logics}, BOOKTITLE = {Proceedings of the International Workshop on Description Logics (DL'2002)}, PADDRESS = {Aachen, Germany}, ADDRESS = {Toulouse, France}, PUBLISHER = {CEUR}, SERIES = {CEUR Workshop Proceedings}, VOLUME = {53}, YEAR = {2002}, PAGES = {25--36}, } @INPROCEEDINGS{GeorgievaMaier2005, AUTHOR = {Georgieva, Lilia and Maier, Patrick}, EDITOR = {Aichernig, Bernhard K. and Beckert, Bernhard}, TITLE = {Description Logics for Shape Analysis}, BOOKTITLE = {Third IEEE International Conference on Software Engineering and Formal Methods (SEFM 2005)}, ORGANIZATION = {IEEE Computer Society}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Koblenz, Germany}, PUBLISHER = {IEEE}, MONTH = {September}, ISBN = {0-7695-2435-4}, YEAR = {2005}, PAGES = {321--330}, ABSTRACT = {Verification of programs requires reasoning about sets of program states. In case of programs manipulating pointers, program states are pointer graphs. Verification of such programs involves reasoning about unbounded sets of graphs. Three-valued shape analysis (Sagiv et. al.) is an approach based on explicit manipulation of 3-valued shape graphs, which abstract sets of pointer graphs. Other approaches use symbolic representations, e.g. by describing (sets of) graphs as logical formulas. Unfortunately, many resulting logics are either undecidable or cannot express crucial properties like reachability and separation. In this paper, we investigate an alternative approach. We study well-known description logics as a framework for symbolic shape analysis. We propose a predicate abstraction based shape analysis, parameterized by description logics to represent the abstraction predicates. Depending on the particular logic chosen sharing, reachability and separation in pointer data structures are expressible.}, } @MASTERSTHESIS{Gerber-Mastersthesis95, AUTHOR = {Gerber, Christian}, TITLE = {Entwicklung eines Algorithmus zur effizienten Anfragebeantwortung f{\"u}r eine terminologische Wissensrepr{\"a}sentationssprache}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {September}, YEAR = {1995}, } @INPROCEEDINGS{GK2007, AUTHOR = {Ganzinger, Harald and Korovin, Konstantin}, EDITOR = {Hermann, Miki and Voronkov, Andrei}, TITLE = {Theory Instantiation}, BOOKTITLE = {Logic for Programming, Artificial Intelligence, and Reasoning : 13th International Conference, LPAR 2006}, PADDRESS = {Berlin, Germany}, ADDRESS = {Phnom Penh, Cambodia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {4246}, ISBN = {3-540-48281-4}, DOI = {10.1007/11916277_34}, YEAR = {2006}, PAGES = {497--511}, } @BOOK{GKNO97, EDITOR = {Gabbay, Dov M. and Kruse, Rudolf and Nonnengart, Andreas and Ohlbach, Hans J{\"u}rgen}, TITLE = {Qualitative and Quantitative Practical Reasoning}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1244}, ISBN = {3-540-63095-3}, YEAR = {1997}, PAGES = {602}, NOTE = {Proceedings of the First International Joint Conference on Qualitative and Quantitative Practical Reasoning, ECSQARU/FAPR'97, Bad Honnef, Germany}, } @INPROCEEDINGS{GoebelMaier2000, AUTHOR = {G{\"o}bel, Manfred and Maier, Patrick}, EDITOR = {Ganzha, Victor G. and Mayr, Ernst W. and Vorozhtsov, Evgenii V.}, TITLE = {Three Remarks on Comprehensive {Gr{\"o}bner} and {SAGBI} Bases}, BOOKTITLE = {Proceedings of the 3rd Workshop on Computer Algebra in Scientific Computing (CASC-2000)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Samarkand, Uzbekistan}, PUBLISHER = {Springer}, ISBN = {3-540-41040-6}, YEAR = {2000}, PAGES = {191--202}, ABSTRACT = {This note presents new complexity results for the comprehensive Gr\"ob\-ner bases (CGB) algorithm in the special case of one main variable and two polynomials, a general remark about CGB for parameterized binomial ideals, and it introduces the concept of comprehensive SAGBI bases together with a first application in invariant theory.}, } @INPROCEEDINGS{GorankoHustadtSchmidtVakarelov04a, AUTHOR = {Goranko, Valentin and Hustadt, Ullrich and Schmidt, Renate A. and Vakarelov, Dimiter}, EDITOR = {Berghammer, Rudolf and M{\"o}ller, Bernhard and Struth, Georg}, TITLE = {{SCAN} is complete for all {Sahlqvist} formulae}, BOOKTITLE = {Relational and Kleene-Algebraic Methods in Computer Science: 7th International Seminar on Relational Methods in Computer Science and 2nd International Workshop on Applications of Kleene Algebra}, PADDRESS = {Berlin, Germany}, ADDRESS = {Bad Malente, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3051}, ISBN = {3-540-22145-X}, YEAR = {2004}, PAGES = {149--162}, ABSTRACT = {SCAN is an algorithm for reducing monadic existential second-order logic formulae to equivalent simpler formulae, often first-order logic formulae. It is provably impossible for such a reduction to first-order logic to be always successful, even if there is an equivalent first-order formula for a second-order logic formula. In this paper we show that SCAN successfully computes the first-order equivalents of all Sahlqvist formulae in the classical (multi-)modal language.}, } @INPROCEEDINGS{Graf-94-cade, AUTHOR = {Graf, Peter}, EDITOR = {Bundy, Alan}, TITLE = {Extended Path-Indexing}, BOOKTITLE = {Proceedings of the 12th International Conference on Automated Deduction (CADE-12)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Nancy, France}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {814}, YEAR = {1994}, PAGES = {514--528}, NOTE = {There is an extended version of this paper published as report MPII-I-93-253}, ABSTRACT = {The performance of a theorem prover crucially depends on the speed of the basic retrieval operations, such as finding terms that are unifiable with (instances of, or more general than) some query term. Among the known indexing methods for term retrieval in deduction systems, Path--Indexing exhibits a good performance in general. However, as Path--Indexing is not a perfect filter, the candidates found by this method have still to be subjected to a unification algorithm in order to detect occur--check failures and indirect clashes. As perfect filters, discrimination trees and abstraction trees thus outperform Path--Indexing in some cases. We present an improved version of Path--Indexing that provides both the query trees and the Path--Index with indirect clash and occur--check information. Thus compared to the standard method we dismiss much more terms as possible candidates.}, } @PHDTHESIS{Graf-95-phd, AUTHOR = {Graf, Peter}, TITLE = {Term Indexing}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, YEAR = {1995}, } @INPROCEEDINGS{Graf-95-rta, AUTHOR = {Graf, Peter}, EDITOR = {Bundy, Alan}, TITLE = {Substitution Tree Indexing}, BOOKTITLE = {Proceedings of the 6th International Conference on Rewriting Techniques and Applications (RTA-95)}, PADDRESS = {Heidelberg, Germany}, ADDRESS = {Kaiserslautern, Germany}, PUBLISHER = {Springer}, MONTH = {April}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {914}, YEAR = {1995}, PAGES = {117--131}, NOTE = {There is an extended version of this paper published as report MPII-I-94-251}, ABSTRACT = {This article addresses the problem of maintaining and retrieving first-order predicate calculus terms in context of automatic reasoning. A new indexing technique that accelerates the speed of the basic retrieval operations, such as finding complementary literals in resolution theorem proving or finding critical pairs during completion is presented. Subsumption and reduction are also supported. Moreover, the new index not only provides maintenance and efficient retrieval of terms but also of idempotent substitutions. Substitution trees achieve maximal search speed paired with minimal memory requirements in various experiments and outperform traditional techniques such as path indexing, discrimination tree indexing and abstraction trees by combining their advantages and adding some new features.}, } @BOOK{Graf-96-LNAI, AUTHOR = {Graf, Peter}, EDITOR = {Carbonell, J. G. and Siekmann, J.}, TITLE = {Term Indexing}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1053}, ISBN = {3-540-61040-5}, YEAR = {1996}, PAGES = {284}, } @INPROCEEDINGS{Graf96-CADE-13, AUTHOR = {Graf, Peter}, EDITOR = {McRobbie, M. A. and Slaney, J. K.}, TITLE = {Path indexing for {AC}-theories}, BOOKTITLE = {Proceedings of the 13th International Conference on Automated Deduction (CADE-13)}, TYPE = {Full Conference Paper}, PADDRESS = {Berlin, Germany}, ADDRESS = {New Brunswick, New Jersey, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1104}, ISBN = {3540615113}, YEAR = {1996}, PAGES = {718--732}, } @MASTERSTHESIS{GrafDipl1992, AUTHOR = {Graf, Peter}, TITLE = {Unification Using Dynamic Sorts}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1992}, } @INPROCEEDINGS{GrafMeyer96, AUTHOR = {Graf, Peter and Meyer, Christoph}, EDITOR = {McRobbie, M. A. and Slaney, J. K.}, TITLE = {Advanced indexing operations on substitution trees}, BOOKTITLE = {Proceedings of the 13th International Conference on Automated Deduction (CADE-13)}, TYPE = {Full paper}, PADDRESS = {Berlin, Germany}, ADDRESS = {New Brunswick, New Jersey, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1104}, ISBN = {3-540-61-511-3}, YEAR = {1996}, PAGES = {553--567}, } @MASTERSTHESIS{Grenner01, AUTHOR = {Grenner, Ingo}, TITLE = {{Die Erzeugung von Schnittebenen mit maximalem Verletzungsgrad und deren Einsatz im Branch-and-Cut Verfahren}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {2001}, NOTE = {1.7}, } @ARTICLE{GSW-i-and-c, AUTHOR = {Ganzinger, Harald and Sofronie-Stokkermans, Viorica and Waldmann, Uwe}, JOURNAL = {Information and Computation}, TITLE = {Modular Proof Systems for Partial Functions with {Evans} Equality}, NUMBER = {10}, PUBLISHER = {Elsevier}, MONTH = {October}, VOLUME = {204}, ISBN = {0890-5401}, YEAR = {2006}, PAGES = {1453--1492}, ABSTRACT = {The paper presents a modular superposition calculus for the combination of first-order theories involving both total and partial functions. Modularity means that inferences are pure, only involving clauses over the alphabet of either one, but not both, of the theories. The calculus is shown to be complete provided that functions that are not in the intersection of the component signatures are declared as partial. This result also means that if the unsatisfiability of a goal modulo the combined theory does not depend on the totality of the functions in the extensions, the inconsistency will be effectively found. Moreover, we consider a constraint superposition calculus for the case of hierarchical theories and show that it has a related modularity property. Finally we identify cases where the partial models can always be made total so that modular superposition is also complete with respect to the standard (total function) semantics of the theories.}, } @ARTICLE{GurevichVeanes99, AUTHOR = {Gurevich, Yuri and Veanes, Margus}, JOURNAL = {Information and Computation}, TITLE = {Logic with Equality: Partisan Corroboration and Shifted Pairing}, NUMBER = {2}, PUBLISHER = {Academic Press}, VOLUME = {152}, YEAR = {1999}, PAGES = {205--235}, ABSTRACT = {Herbrand's theorem plays a fundamental role in automated theorem proving methods based on tableaux. The crucial step in procedures based on such methods can be described as the \emph{corroboration} problem or the \emph{Herbrand skeleton} problem, where, given a positive integer $m$, called \emph{multiplicity}, and a quantifier free formula, one seeks a valid disjunction of $m$ instantiations of that formula. In the presence of \emph{equality}, which is the case in this paper, this problem was recently shown to be undecidable. The main contributions of this paper are two theorems. The first, the \emph{Partisan Corroboration Theorem}, relates corroboration problems with different multiplicities. The second, the \emph{Shifted Pairing Theorem}, is a finite tree automata formalization of a technique for proving undecidability results through direct encodings of valid Turing machine computations. These theorems are used in the paper to explain and sharpen several recent undecidability results related to the \emph{corroboration} problem, the \emph{simultaneous rigid E-unification} problem and the \emph{prenex fragment of intuitionistic logic with equality}.}, } @TECHREPORT{HaehnleKerberEtAl96, AUTHOR = {H{\"a}hnle, Reiner and Kerber, Manfred and Weidenbach, Christoph}, TITLE = {{Common Syntax of the DFG-Schwerpunktprogramm ``Deduktion''}}, INSTITUTION = {Universit{\"a}t Karlsruhe}, TYPE = {Interner Bericht}, ADDRESS = {Karlsruhe, Fakult{\"a}t f{\"u}r Informatik, Germany}, NUMBER = {10/96}, MONTH = {April}, YEAR = {1996}, PAGES = {10}, } @MASTERSTHESIS{Hagemann2008, AUTHOR = {Hagemann, Willem}, TITLE = {Formalisierung der Arithmetik}, SCHOOL = {Universit{\"a}t G{\"o}ttingen}, TYPE = {Diploma thesis}, YEAR = {2005}, } @INPROCEEDINGS{Hanus91a, AUTHOR = {Hanus, Michael}, EDITOR = {Boley, H. and Richter, M.M.}, TITLE = {Efficient Implementation of Narrowing and Rewriting}, BOOKTITLE = {Proc. Intern. Workshop on Processing Declarative Knowledge}, PADDRESS = {Berlin, Germany}, ADDRESS = {Kaiserslautern, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {567}, YEAR = {1991}, PAGES = {344--365}, ABSTRACT = {We present an efficient implementation method for a language that amalgamates functional and logic programming styles. The operational semantics of the language consists of resolution to solve predicates and narrowing and rewriting to evaluate functional expressions. The implementation is based on an extension of the Warren Abstract Machine (WAM). This extension causes no overhead for pure logic programs and allows the execution of functional programs by narrowing and rewriting with the same efficiency as their relational equivalents. Moreover, there are many cases where functional programs are more efficiently executed than their relational equivalents.}, } @INPROCEEDINGS{Hanus91b, AUTHOR = {Hanus, Michael}, EDITOR = {Abramsky, S. and Maibaum, T.S.E.}, TITLE = {Parametric Order-Sorted Types in Logic Programming}, BOOKTITLE = {Proceedings of the International Joint Conference on Theory and Practice of Software Development (TAPSOFT-91)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Brighton, UK}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {494}, YEAR = {1991}, PAGES = {181--200}, ABSTRACT = {This paper proposes a type system for logic programming where types are structured in two ways. Firstly, functions and predicates may be declared with types containing type parameters which are universally quantified over all types. In this case each instance of the type declaration can be used in the logic program. Secondly, types are related by subset inclusions. In this case a function or predicate can be applied to all subtypes of its declared type. While previous proposals for such type systems have strong restrictions on the subtype relation, we assume that the subtype order is specified by Horn clauses for the subtype relation $\leq$. This allows the declaration of a lot of interesting type structures, e.g., type constructors which are monotonic as well as anti-monotonic in their arguments. For instance, parametric order-sorted type structures for logic programs with higher-order predicates can be specified in our framework. This paper presents the declarative and operational semantics of the typed logic language. The operational semantics requires a unification procedure on well-typed terms. This unification procedure is described by a set of transformation rules which generate a set of type constraints from a given unification problem. The solvability of these type constraints is decidable for particular type structures.}, } @ARTICLE{Hanus91c, AUTHOR = {Hanus, Michael}, JOURNAL = {Theoretical Computer Science}, TITLE = {Horn Clause Programs with Polymorphic Types: Semantics and Resolution}, PUBLISHER = {North-Holland Publishing Co.}, VOLUME = {89}, ISBN = {0304-3975}, YEAR = {1991}, PAGES = {63--106}, ABSTRACT = {This paper presents a Horn clause logic where functions and predicates are declared with polymorphic types. Types are parameterized with type variables. This leads to an ML-like polymorphic type system. A type declaration of a function or predicate restricts the possible use of this function or predicate so that only certain terms are allowed to be arguments for this function or predicate. The semantic models for polymorphic Horn clause programs are defined and a resolution method for this kind of logic programs is given. It will be shown that several optimizations in the resolution method are possible for specific kinds of programs. Moreover, it is shown that higher-order programming techniques can be applied in our framework.}, } @INPROCEEDINGS{Hanus92a, AUTHOR = {Hanus, Michael}, EDITOR = {Kirchner, H{\'e}l{\`e}ne and Levi, Georgio}, TITLE = {Incremental Rewriting in Narrowing Derivations}, BOOKTITLE = {Proceedings of the 3rd International Conference on Algebraic and Logic Programming (ALP-92)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Volterra, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {632}, YEAR = {1992}, PAGES = {228--243}, ABSTRACT = {The operational semantics of many proposals for the integration of functional and logic programming languages is based on narrowing. In order to reduce the search space and to prefer deterministic computations, the goal is rewritten to normal form between narrowing steps (normalizing narrowing). This rewriting process may be costly since the entire goal must be reduced to normal form after each narrowing step. We propose a useful optimization of the rewriting process: since the goal is in normal form before the narrowing step is applied and the narrowing step changes only small parts of the goal, rewriting can be restricted to a small number of positions in the narrowed goal in order to compute a new normal form. This optimization can speed up the execution mechanism of programming languages based on normalizing narrowing like SLOG or ALF.}, } @INPROCEEDINGS{Hanus92b, AUTHOR = {Hanus, Michael}, EDITOR = {Apt, Krzysztof}, TITLE = {On the Completeness of Residuation}, BOOKTITLE = {Proceedings of the 1992 Joint International Conference and Symposium on Logic Programming}, PADDRESS = {Cambridge, USA}, ADDRESS = {Washington, D.C.}, PUBLISHER = {MIT Press}, YEAR = {1992}, PAGES = {192--206}, NOTE = {Extended version to appear in Journal of Logic Programming}, ABSTRACT = {Residuation is an operational mechanism for the integration of functions into logic programming languages. The residuation principle delays the evaluation of functions during the unification process until the arguments are sufficiently instantiated. This has the advantage that the deterministic nature of functions is preserved but the disadvantage of incompleteness: if the variables in a delayed function call are not instantiated by the logic program, this function can never be evaluated and some answers which are logical consequences of the program are lost. In this paper we present a method for detecting such situations. The method is based on a compile-time analysis of the program and approximates the possible residuations and instantiation states of variables during program execution.}, } @INPROCEEDINGS{Hanus92c, AUTHOR = {Hanus, Michael}, EDITOR = {Bruynooghe, Maurice and Wirsing, Martin}, TITLE = {Improving Control of Logic Programs by Using Functional Logic Languages}, BOOKTITLE = {Proceedings 4th International Symposium on Programming Language Implementation and Logic Programming}, PADDRESS = {Berlin, Germany}, ADDRESS = {Leuven, Belgium}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {631}, YEAR = {1992}, PAGES = {1--23}, ABSTRACT = {This paper shows the advantages of amalgamating functional and logic programming languages. In comparison with pure functional languages, an amalgamated functional logic language has more expressive power. In comparison with pure logic languages, functional logic languages have a better control behaviour. The latter will be shown by presenting methods to translate logic programs into a functional logic language with a narrowing/rewriting semantics. The translated programsproduce the same set of answers and have at least the same efficiency as the original programs. But in many cases the control behaviour of the translated programs is improved. This requires the addition of further knowledge to the programs. We discuss methods for this and show the gain in efficiency by means of several examples.}, } @INCOLLECTION{Hanus92d, AUTHOR = {Hanus, Michael}, EDITOR = {Pfenning, Frank}, TITLE = {Logic Programming with Type Specifications}, BOOKTITLE = {Types in Logic Programming}, CHAPTER = {3}, ADDRESS = {Cambridge, USA}, PUBLISHER = {MIT Press}, YEAR = {1992}, PAGES = {91--140}, ABSTRACT = {In this chapter, we propose a framework for logic programming with different type systems. In this framework a typed logic program consists of a type specification and a Horn clause program which is well-typed with respect to the type specification. The type specification defines all types which can be used in the logic program. Relations between types are expressed by equations on the level of types. This permits the specification of many-sorted, order-sorted, polymorphic and polymorphically order-sorted type systems. We present the declarative semantics of our framework and two proof procedures (deduction and resolution) for typed logic programs. An interesting application is a type system that combines parametric polymorphism with order-sorted typing and permits higher-order logic programming. Moreover, our framework sheds some new light on the r\^{o}le of types in logic programming.}, } @INPROCEEDINGS{Hanus93a, AUTHOR = {Hanus, Michael}, EDITOR = {Warren, David Scott}, TITLE = {Analysis of Nonlinear Constraints in {CLP($\cal{R}$)}}, BOOKTITLE = {Proceedings of the 10th International Conference on Logic Programming (ICLP '93)}, PADDRESS = {Cambridge, USA}, ADDRESS = {Budapest, Hungary}, PUBLISHER = {MIT Press}, YEAR = {1993}, PAGES = {83--99}, NOTE = {Extended version to appear in New Generation Computing}, ABSTRACT = {Solving nonlinear constraints over real numbers is a complex problem. Hence constraint logic programming languages like CLP($\cal R$) or Prolog III solve only linear constraints and delay nonlinear constraints until they become linear. This efficient implementation method has the disadvantage that sometimes computed answers are unsatisfiable or infinite loops occur due to the unsatisfiability of delayed nonlinear constraints. These problems could be solved by using a more powerful constraint solver which can deal with nonlinear constraints like in RISC-CLP(Real). Since such powerful constraint solvers are not very efficient, we propose a compromise between these two extremes. We characterize a class of CLP($\cal R$) programs for which all delayed nonlinear constraints become linear at run time. Programs belonging to this class can be safely executed with the efficient CLP($\cal R$) method while the remaining programs need a more powerful constraint solver.}, } @INPROCEEDINGS{Hanus93d, AUTHOR = {Hanus, Michael}, TITLE = {Towards the Global Optimization of Functional Logic Programs}, BOOKTITLE = {Proc.~Workshop on Global Compilation, International Logic Programming Symposium}, ADDRESS = {Vancouver, Canada}, YEAR = {1993}, PAGES = {83--97}, ABSTRACT = {Functional logic languages amalgamate functional and logic programming programming paradigms. They can be efficiently implemented by extending techniques known from logic programming. In this paper we show how global information about the call modes of functions can be used to optimize the compilation of functional logic programs. Since mode information has been successfully used to improve the implementation of pure logic programs and these techniques can be applied to implementations of functional logic programs as well, we concentrate on optimizations which are unique to the operational semantics of functional logic programs. We define a suitable notion of modes for functional logic programs and present compile-time techniques to optimize the normalization process during the execution of functional logic programs.}, } @INPROCEEDINGS{Hanus94ESOP, AUTHOR = {Hanus, Michael}, EDITOR = {Sannella, Don}, TITLE = {Lazy Unification with Simplification}, BOOKTITLE = {Proceedings of the 5th European Symposium on Programming Languages and Systems (ESOP'94)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Edinburgh, UK}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {788}, YEAR = {1994}, PAGES = {272--286}, ABSTRACT = {Unification in the presence of an equational theory is an important problem in theorem-proving and in the integration of functional and logic programming languages. This paper presents an improvement of the proposed lazy unification methods by incorporating simplification into the unification process. Since simplification is a deterministic computation process, more efficient unification algorithms can be achieved. Moreover, simplification reduces the search space so that in some cases infinite search spaces are reduced to finite ones. We show soundness and completeness of our method for equational theories represented by ground confluent and terminating rewrite systems which is a reasonable class w.r.t.\ functional logic programming.}, } @ARTICLE{Hanus94JLP, AUTHOR = {Hanus, Michael}, JOURNAL = {Journal of Logic Programming}, TITLE = {The Integration of Functions into Logic Programming: From Theory to Practice}, ADDRESS = {Amsterdam, the Netherlands}, PUBLISHER = {Elsevier}, VOLUME = {19 \& 20}, ISBN = {0743-1066}, YEAR = {1994}, PAGES = {583--628}, NOTE = {Also available as Research Report MPI-I-94-201, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken}, ABSTRACT = {Functional and logic programming are the most important declarative programming paradigms, and interest in combining them has grown over the last decade. Early research concentrated on the definition and improvement of execution principles for such integrated languages, while more recently efficient implementations of these execution principles have been developed so that these languages became relevant for practical applications. In this paper we survey the development of the operational semantics as well as the improvement of the implementation of functional logic languages.}, } @INPROCEEDINGS{Hanus94PLILP, AUTHOR = {Hanus, Michael}, EDITOR = {Hermenegildo, Manuel and Penjam, Jaan}, TITLE = {Combining Lazy Narrowing and Simplification}, BOOKTITLE = {Proceedings of the 6th International Symposium on Programming Language Implementation and Logic Programming (PLILP'94)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Madrid, Spain}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {844}, YEAR = {1994}, PAGES = {370--384}, ABSTRACT = {Languages that integrate functional and logic programming styles with a complete operational semantics are based on narrowing. In order to avoid useless computations and to deal with infinite data structures, lazy narrowing strategies have been proposed in the past. This paper presents an important improvement of lazy narrowing by incorporating deterministic simplification steps into lazy narrowing derivations. These simplification steps reduce the search space so that in some cases infinite search spaces are reduced to finite ones. We show that the completeness of lazy narrowing is not destroyed by the simplification process and demonstrate the improved operational behavior by means of several examples.}, } @ARTICLE{hanus95a, AUTHOR = {Hanus, Michael}, JOURNAL = {New Generation Computing}, TITLE = {Compile-Time Analysis of Nonlinear Constraints in {CLP(R)}}, NUMBER = {2}, PUBLISHER = {Ohmsha Ltd}, VOLUME = {13}, ISBN = {0288-3635}, YEAR = {1995}, PAGES = {155--186}, ABSTRACT = {Solving nonlinear constraints over real numbers is a complex problem. Hence constraint logic programming languages like CLP($\cal R$) or Prolog III solve only linear constraints and delay nonlinear constraints until they become linear. This efficient implementation method has the disadvantage that sometimes computed answers are unsatisfiable or infinite loops occur due to the unsatisfiability of delayed nonlinear constraints. These problems could be solved by using a more powerful constraint solver which can deal with nonlinear constraints like in RISC-CLP(Real). Since such powerful constraint solvers are not very efficient, we propose a compromise between these two extremes. We characterize a class of CLP($\cal R$) programs for which all delayed nonlinear constraints become linear at run time. Programs belonging to this class can be safely executed with the efficient CLP($\cal R$) method while the remaining programs need a more powerful constraint solver.}, } @INPROCEEDINGS{Hanus95ICLP, AUTHOR = {Hanus, Michael}, TITLE = {On Extra Variables in (Equational) Logic Programming}, BOOKTITLE = {Proceedings of the Twelfth International Conference on Logic Programming}, PADDRESS = {Cambridge, USA}, ADDRESS = {Kanagawa, Japan}, PUBLISHER = {MIT Press}, YEAR = {1995}, PAGES = {665--679}, ABSTRACT = {Extra variables in a clause are variables which occur in the body but not in the head. It has been argued that extra variables are necessary and contribute to the expressive power of logic languages. In the first part of this paper, we show that this is not true in general. For this purpose, we provide a simple syntactic transformation of each logic program into a logic program without extra variables, and we show a strong correspondence between the original and the transformed program. In the second and main part of this paper, we use a similar technique to provide new completeness results for equational logic programs with extra variables. In equational logic programming it is well known that extra variables cause problems since narrowing, the standard operational semantics for equational logic programming, may become incomplete in the presence of extra variables. Using a simple syntactic transformation, we derive a number of new completeness results for narrowing. In particular, we show the completeness of narrowing strategies in the presence of nonterminating functions and extra variables in right-hand sides of rewrite rules. Using these results, current functional logic languages can be extended in a practically useful way.}, } @ARTICLE{Hanus95JLP, AUTHOR = {Hanus, Michael}, JOURNAL = {Journal of Logic Programming}, TITLE = {Analysis of Residuating Logic Programs}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {3}, PUBLISHER = {Elsevier}, VOLUME = {24}, ISBN = {0743-1066}, YEAR = {1995}, PAGES = {219--245}, ABSTRACT = {Residuation is an operational mechanism for the integration of functions into logic programming languages. The residuation principle delays the evaluation of functions during the unification process until the arguments are sufficiently instantiated. This has the advantage that the deterministic nature of functions is preserved, but the disadvantage of incompleteness: if the variables in a delayed function call are not instantiated by the logic program, this function can never be evaluated, and some answers which are logical consequences of the program are lost. In order to detect such situations at compile time, we present an abstract interpretation algorithm for this kind of programs. The algorithm approximates the possible residuations and instantiation states of variables during program execution. If the algorithm computes an empty residuation set for a goal, then it is ensured that the concrete execution of the goal does not end with a nonempty set of residuations which cannot be evaluated due to insufficient instantiation of argument variables.}, } @PHDTHESIS{HanusHabil1994, AUTHOR = {Hanus, Michael}, TITLE = {Thema der Antrittsvorlesung: Deklarative Programmierparadigmen und ihre Integration}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Habilitation thesis}, MONTH = {May}, YEAR = {1994}, } @INPROCEEDINGS{HanusJosephs93c, AUTHOR = {Hanus, Michael and Josephs, Berthold}, EDITOR = {Bruynooghe, Maurice and Penjam, Jaan}, TITLE = {A Debugging Model for Functional Logic Programs}, BOOKTITLE = {Proceedings of the 5th International Symposium on Programming Language Implementation and Logic Programming (PLILP-93)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Tallinn, Estonia}, PUBLISHER = {Springer}, MONTH = {October}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {714}, YEAR = {1993}, PAGES = {28--43}, NOTE = {Also available as Research Report MPI-I-93-222}, ABSTRACT = {This paper presents a box-oriented debugging model for the functional logic language ALF. Due to the sophisticated operational semantics of ALF which is based on innermost basic narrowing with simplification, the debugger must reflect the application of the different computation rules during program execution. Hence our debugging model includes not only one box type as in Byrd's debugging model for logic programs but several different kinds of boxes corresponding to the various computation rules of the functional logic language (narrowing, simplification, etc.). Moreover, additional box types are introduced in order to allow skips over (sometimes) uninteresting program parts like proofs of the condition in a conditional equation. Since ALF is a genuine amalgamation of functional and logic languages, our debugging model subsumes operational aspects of both kinds of languages. As a consequence, it can be also used for pure logic languages, pure functional languages with eager evaluation, or functional logic languages with a less sophisticated operational semantics like SLOG or eager BABEL.}, } @INPROCEEDINGS{HanusZartmann94SAS, AUTHOR = {Hanus, Michael and Zartmann, Frank}, EDITOR = {Le Charlier, Baudouin}, TITLE = {Mode Analysis of Functional Logic Programs}, BOOKTITLE = {Proceedings of the 1st International Static Analysis Symposium (SAS'94)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Namur, Belgium}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {864}, YEAR = {1994}, PAGES = {26--42}, ABSTRACT = {Functional logic languages amalgamate functional and logic programming paradigms. They can be efficiently implemented by extending techniques known from logic programming. Such implementations can be largely improved if information about the run-time behavior, in particular the modes of function calls, is available at compile time. In this paper we present a framework to derive such global information. The concrete operational semantics considered in this paper is normalizing innermost narrowing, which combines the deterministic reduction principle of functional languages with the nondeterministic search principle of logic languages. Due to the normalization process between narrowing steps, standard analysis frameworks for logic programming cannot be applied. Therefore we develop new techniques to correctly approximate the effect of the intermediate normalization process.}, } @INPROCEEDINGS{Hillenbrand2003, AUTHOR = {Hillenbrand, Thomas}, EDITOR = {Dahn, Ingo and Vigneron, Laurent}, TITLE = {Citius altius fortius: Lessons learned from the Theorem Prover {WALDMEISTER}}, BOOKTITLE = {Proceedings of the 4th International Workshop on First Order Theorem Proving, FTP'03}, TYPE = {Invited Talk}, PADDRESS = {Amsterdam, The Netherlands}, ADDRESS = {Valencia, Spain}, PUBLISHER = {Elsevier}, MONTH = {June}, SERIES = {Electronic Notes in Theoretical Computer Science}, VOLUME = {86.1}, YEAR = {2003}, PAGES = {1--13}, ABSTRACT = {In the last years, the development of automated theorem provers has been advancing in a so to speak Olympic spirit, following the motto "faster, higher, stronger"; and the {Waldmeister} system has been a part of that endeavour. We will survey the concepts underlying this prover, which implements Knuth-Bendix completion in its unfailing variant. The system architecture is based on a strict separation of active and passive facts, and is realized via specifically tailored representations for each of the central data structures: indexing for the active facts, set-based compression for the passive facts, successor sets for the conjectures. In order to cope with large search spaces, specialized redundancy criteria are employed, and the empirically gained control knowledge is integrated to ease the use of the system. We conclude with a discussion of strengths and weaknesses, and a view of future prospects.}, } @INPROCEEDINGS{Hillenbrand2004, AUTHOR = {Hillenbrand, Thomas}, EDITOR = {Sattler, Ulrike}, TITLE = {A Superposition View on {Nelson-Oppen}}, BOOKTITLE = {Contributions to the Doctoral Programme of the 2nd International Joint Conference on Automated Reasoning}, PADDRESS = {Aachen}, ADDRESS = {Cork, Ireland}, PUBLISHER = {CEUR}, MONTH = {July}, SERIES = {CEUR Workshop Proceedings}, VOLUME = {106}, ISBN = {1613-0073}, YEAR = {2004}, PAGES = {16--20}, } @INPROCEEDINGS{HillenbrandLoechner2001, AUTHOR = {Hillenbrand, Thomas and L{\"o}chner, Bernd}, EDITOR = {de Nivelle, Hans and Schulz, Stephan}, TITLE = {The Next {WALDMEISTER} Loop (Extended Abstract)}, BOOKTITLE = {Proceedings of the Second International Workshop on the Implementation of Logics, IWIL 2001}, PADDRESS = {Saarbr{\"u}cken, Germany}, ADDRESS = {Havana, Cuba}, PUBLISHER = {Max-Planck-Institut f{\"u}r Informatik}, MONTH = {November}, SERIES = {Research Report}, VOLUME = {MPI-I-2001-2-006}, YEAR = {2001}, PAGES = {13--21}, } @INPROCEEDINGS{HillenbrandTopicWeidenbach2005, AUTHOR = {Hillenbrand, Thomas and Topic, Dalibor and Weidenbach, Christoph}, EDITOR = {Ahrendt, Wolfgang and Baumgartner, Peter and de Nivelle, Hans}, TITLE = {Sudokus as Logical Puzzles}, BOOKTITLE = {Proceedings of the Third Workshop on Disproving}, PADDRESS = {n.a.}, ADDRESS = {Seattle, USA}, PUBLISHER = {none}, YEAR = {2006}, PAGES = {2--12}, } @INPROCEEDINGS{HL02-CADE18, AUTHOR = {Hillenbrand, Thomas and L{\"o}chner, Bernd}, EDITOR = {Voronkov, Andrei}, TITLE = {The Next {WALDMEISTER} Loop}, BOOKTITLE = {Automated deduction, CADE-18 : 18th International Conference on Automated Deduction}, PADDRESS = {Heidelberg, Germany}, ADDRESS = {Copenhagen, Denmark}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2392}, ISBN = {3-540-43931-5}, YEAR = {2002}, PAGES = {486--500}, ABSTRACT = { In saturation-based theorem provers, the reasoning process consists in constructing the closure of an axiom set under inferences. As is well-known, this process tends to quickly fill the memory available unless preventive measures are employed. For implementations based on the DISCOUNT loop, the passive facts are responsible for most of the memory consumption. We present a refinement of that loop allowing such a compression that the space needed for the passive facts is linearly bound by the number of active facts. In practice, this will reduce memory consumption in the WALDMEISTER system by more than one order of magnitude as compared to previous compression schemes.}, } @INPROCEEDINGS{HoenickeMaier2005, AUTHOR = {Hoenicke, Jochen and Maier, Patrick}, EDITOR = {Fitzgerald, John and Hayes, Ian J. and Tarlecki, Andrzej}, TITLE = {Model-Checking of Specifications Integrating Processes, Data and Time}, BOOKTITLE = {FM 2005: Formal Methods; International Symposium of Formal Methods Europe}, ORGANIZATION = {Formal Methods Europe (FME)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Newcastle, UK}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3582}, ISBN = {3-540-27882-6}, YEAR = {2005}, PAGES = {465--480}, ABSTRACT = {We present a new model-checking technique for CSP-OZ-DC, a combination of CSP, Object-Z and Duration Calculus, that allows reasoning about systems exhibiting communication, data and real-time aspects. As intermediate layer we will use a new kind of timed automata that preserve events and data variables of the specification. These automata have a simple operational semantics that is amenable to verification by a constraint-based abstraction-refinement model checker. By means of a case study, a simple elevator parameterised by the number of floors, we show that this approach admits model-checking parameterised and infinite state real-time systems.}, } @BOOK{Hoffmann2003a, AUTHOR = {Hoffmann, J{\"o}rg}, TITLE = {Utilizing Problem Structure in Planning: A Local Search Approach}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2854}, ISBN = {3-540-20259-5}, YEAR = {2003}, PAGES = {264}, } @ARTICLE{Hoffmann2003b, AUTHOR = {Hoffmann, J{\"o}rg}, JOURNAL = {Journal of Artificial Intelligence Research}, TITLE = {The {Metric-FF} Planning System: Translating ``Ignoring Delete Lists'' To Numeric State Variables}, NUMBER = {1}, PUBLISHER = {Morgan Kaufmann}, MONTH = {December}, VOLUME = {20}, ISBN = {1076-9757}, YEAR = {2003}, PAGES = {51}, } @ARTICLE{Hoffmann2005, AUTHOR = {Hoffmann, J{\"o}rg}, JOURNAL = {Journal of Artificial Intelligence Research}, TITLE = {Where Ignoring Delete Lists Works: Local Search Topology in Planning Benchmarks}, ADDRESS = {Menlo Park, USA}, PUBLISHER = {AAAI}, MONTH = {November}, VOLUME = {24}, ISBN = {1076-9757}, YEAR = {2005}, PAGES = {685--758}, } @INPROCEEDINGS{HoffmannBrafman2005a, AUTHOR = {Hoffmann, J{\"o}rg and Brafman, Ronen}, EDITOR = {Biundo, Susanne and Meyers, Karen and Rajan, Kanna}, TITLE = {Contingent Planning via Heuristic Forward Search with Implicit Belief States}, BOOKTITLE = {15th International Conference on Automated Planning and Scheduling}, PADDRESS = {Menlo Park, USA}, ADDRESS = {Monterey, USA}, PUBLISHER = {AAAI}, MONTH = {June}, ISBN = {1-57735-220-3}, YEAR = {2005}, PAGES = {71--80}, ABSTRACT = { Contingent planning is the task of generating a conditional plan given uncertainty about the initial state and action effects, but with the ability to observe some aspects of the current world state. Contingent planning can be transformed into an And-Or search problem in belief space, the space whose elements are sets of possible worlds. In \cite{CFF}, we introduced a method for implicitly representing a belief state using a propositional formula that describes the sequence of actions leading to that state. This representation trades off space for time and was shown to be quite effective for conformant planning within a heuristic forward-search planner based on the \ff\ system. In this paper we apply the same architecture to contingent planning. The changes required to adapt the search space representation are small. More effort is required to adapt the relaxed planning problems whose solution informs the forward search algorithm. We propose the targeted use of an additional relaxation, mapping the relaxed {\em contingent} problem into a relaxed {\em conformant} problem. Experimental results show that the resulting planning system, \contff, is highly competitive with the state-of-the-art contingent planners \pond\ and \mbp.}, } @ARTICLE{HoffmannBrafman2006, AUTHOR = {Hoffmann, J{\"o}rg and Brafman, Ronen I.}, JOURNAL = {Artificial Intelligence}, TITLE = {Conformant planning via heuristic forward search: A new approach}, ADDRESS = {Amsterdam, The Netherlands}, PUBLISHER = {Elsevier}, VOLUME = {170}, YEAR = {2006}, PAGES = {507--541}, ABSTRACT = {Conformant planning is the task of generating plans given uncertainty about the initial state and action effects, and without any sensing capabilities during plan execution. The plan should be successful regardless of which particular initial world we start from. It is well known that conformant planning can be transformed into a search problem in belief space, the space whose elements are sets of possible worlds. We introduce a new representation of that search space, replacing the need to store sets of possible worlds with a need to reason about the effects of action sequences. The reasoning is done by implication tests on propositional formulas in conjunctive normal form (CNF) that capture the action sequence semantics. Based on this approach, we extend the classical heuristic forward-search planning system FF to the conformant setting. The key to this extension is an appropriate extension of the relaxation that underlies FF's heuristic function, and of FF's machinery for solving relaxed planning problems: the extended machinery includes a stronger form of the CNF implication tests that we use to reason about the effects of action sequences. Our experimental evaluation shows the resulting planning system to be superior to the state-of-the-art conformant planners MBP, KACMBP, and GPT in a variety of benchmark domains.}, } @ARTICLE{HoffmannEdelkamp2005, AUTHOR = {Hoffmann, J{\"o}rg}, JOURNAL = {Journal of Artificial Intelligence Research}, TITLE = {The Deterministic Part of IPC-4: An Overview}, ADDRESS = {Menlo Park, USA}, PUBLISHER = {AAAI}, MONTH = {October}, VOLUME = {24}, ISBN = {1076-9757}, YEAR = {2005}, PAGES = {519 -- 579}, } @ARTICLE{HoffmannEtal2004, AUTHOR = {Hoffmann, J{\"o}rg and Porteous, Julie and Sebastia, Laura}, JOURNAL = {Journal of Artificial Intelligence Research}, TITLE = {Ordered Landmarks in Planning}, PUBLISHER = {Morgan Kaufmann}, MONTH = {November}, VOLUME = {22}, ISBN = {1076-9757}, YEAR = {2004}, PAGES = {215--278}, } @INPROCEEDINGS{HoffmannEtal2006a, AUTHOR = {Hoffmann, J{\"o}rg and Gomes, Carla and Selman, Bart}, EDITOR = {Long, Derek and Smith, Stephen F. and Borrajo, Daniel and McCluskey, Lee}, TITLE = {Structure and Problem Hardness: Goal Asymmetry and DPLL Proofs in SAT-Based Planning}, BOOKTITLE = {Proceedings of the Sixteenth International Conference on Automated Planning and Scheduling (ICAPS 2006)}, PADDRESS = {Menlo Park, USA}, ADDRESS = {The English Lake District}, PUBLISHER = {AAAI}, ISBN = {978-1-57735-270-9}, YEAR = {2006}, PAGES = {284--293}, ABSTRACT = {In AI Planning, as well as Verification, a successful method is to compile the application into boolean satisfiability (SAT), and solve it with state-of-the-art DPLL-based procedures. There is a lack of formal understanding why this works so well. Focussing on the Planning context, we identify a form of problem structure concerned with the symmetrical or asymmetrical nature of the cost of achieving the individual planning goals. We quantify this sort of structure with a simple numeric parameter called AsymRatio, ranging between 0 and 1. We show empirically that AsymRatio correlates strongly with SAT solver performance in a broad range of Planning benchmarks, including the domains used in the 3rd International Planning Competition. We then examine carefully crafted synthetic planning domains that allow to control the amount of structure, and that are clean enough for a rigorous analysis of the combinatorial search space. The domains are parameterized by size n, and by a structure parameter k, so that AsymRatio is asymptotic to k/n. The CNFs we examine are unsatisfiable, encoding one planning step less than the length of the optimal plan. We prove upper and lower bounds on the size of the best possible DPLL refutations, under different settings of k, as a function of n. We also identify the best possible sets of branching variables (backdoors). With minimum AsymRatio, we prove exponential lower bounds, and identify minimal backdoors of size linear in the number of variables. With maximum AsymRatio, we identify logarithmic DPLL refutations (and backdoors), showing a doubly exponential gap between the two structural extreme cases. This provides a concrete insight into the practical efficiency of modern SAT solvers. }, } @INPROCEEDINGS{HoffmannEtAl2006b, AUTHOR = {Hoffmann, J{\"o}rg and Sabharwal, Ashish and Domshlak, Carmel}, EDITOR = {Long, Derek and Smith, Stephen F. and Borrajo, Daniel and McCluskey, Lee}, TITLE = {Friends or Foes? An {AI} Planning Perspective on Abstraction and Search}, BOOKTITLE = {Proceedings of the Sixteenth International Conference on Automated Planning and Scheduling (ICAPS 2006)}, PADDRESS = {Menlo Park, USA}, ADDRESS = {The English Lake District}, PUBLISHER = {AAAI}, ISBN = {978-1-57735-270-9}, YEAR = {2006}, PAGES = {294--303}, ABSTRACT = {There is increasing awareness that planning and model checking are closely related fields. Abstraction means to perform search in an over-approximation of the original problem instance, with a potentially much smaller state space. This is the most essential method in model checking. One would expect that it can also be made successful in planning. We show, however, that this is likely to not be the case. The main reason is that, while in model checking one traditionally uses blind search to exhaust the state space and prove the absence of solutions, in planning informed search is used to find solutions. We give an exhaustive theoretical and practical account of the use of abstraction in planning. For all abstraction (over-approximation) methods known in planning, we prove that they cannot improve the best-case behavior of informed search. While this is easy to see for heuristic search, we were quite surprised to find that it also holds, in most cases, for the resolution-style proofs of unsolvability underlying SAT-based optimal planners. This result is potentially relevant also for model checking, where SAT-based techniques have recently been combined with abstraction. Exploring the issue in planning practice, we find that even hand-made abstractions do not tend to improve the performance of planners, unless the attacked task contains huge amounts of irrelevance. We relate these findings to the kinds of application domains that are typically addressed in model checking. }, } @INPROCEEDINGS{HoffmannGeffner2003, AUTHOR = {Hoffmann, J{\"o}rg and Geffner, Hector}, EDITOR = {Giunchiglia, Enrico and Muscettola, Nicola and Nau, Dana}, TITLE = {Branching Matters: Alternative Branching in Graphplan}, BOOKTITLE = {13th International Conference on Automated Planning and Scheduling (ICAPS-13)}, PADDRESS = {Menlo Park, USA}, ADDRESS = {Trento, Italy}, PUBLISHER = {AAAI}, MONTH = {June}, ISBN = {1-57735-187-8}, YEAR = {2003}, PAGES = {22--31}, } @INPROCEEDINGS{HoffmannKupferschmid2005, AUTHOR = {Hoffmann, J{\"o}rg}, EDITOR = {Kaelbling, Leslie}, TITLE = {A Covering Problem for Hypercubes}, BOOKTITLE = {Proceedings of the 19th International Joint Conference on Artificial Intelligence}, ADDRESS = {New York, USA}, PUBLISHER = {Morgan Kaufmann}, YEAR = {2005}, PAGES = {579--580}, } @INCOLLECTION{hop94, AUTHOR = {Hopf, J{\"o}rn and Klawonn, Frank}, EDITOR = {Kruse, R. and Palm, R. and Gebhardt, J.}, TITLE = {Learning the Rule Base of a Fuzzy Controller by a Genetic Algorithm}, BOOKTITLE = {Fuzzy Systems in Computer Science}, CHAPTER = {2.4}, ADDRESS = {Braunschweig, Germany}, PUBLISHER = {Friedr. Vieweg \& Sohn}, SERIES = {K{\"u}nstliche Intelligenz}, ISBN = {3-528-05456-5}, YEAR = {1994}, PAGES = {63--74}, ABSTRACT = {For the design of a fuzzy controller it is necessary to choose, besides other parameters, suitable membership functions for the linguistic terms and to determine a rule base.\\ This paper deals with the problem of finding %out the best possible rule a good rule base --- the basis of a fuzzy controller. Consulting experts still is the usual but time--consuming and therefore rather expensive method. Besides, after having designed the controller, one cannot be sure that the rule base %works at its approximative optimum. will lead to near optimal control. This paper shows how to reduce significantly the period of development (and the costs) of fuzzy controllers with the help of genetic algorithms and, above all, how to engender a rule base which is very close to an optimum solution.\\ The example of the inverted pendulum is used to demonstrate how a genetic algori thm can be designed for an automatic construction of a rule base.\\ So this paper does {\em not} deal with the tuning of an existing fuzzy controller but with the genetic (re--)production of rules, even without the need for experts. Thus, a program is engendered, consisting of simple ``{\sl IF \dots THEN \dots}'' instructions.}, } @INPROCEEDINGS{Hopf93a, AUTHOR = {Hopf, J{\"o}rn and Klawonn, Frank}, TITLE = {{Selbstlernende Fuzzy-Controller auf der Basis Genetischer Algorithmen}}, BOOKTITLE = {Fuzzy-Systeme '93 / Management unsicherer Informationen}, ORGANIZATION = {Gesellschaft f{\"u}r Informatik (GI)}, PADDRESS = {Bonn, Germany}, ADDRESS = {Braunschweig, Germany}, PUBLISHER = {Deutsche Informatik-Akademie}, MONTH = {October}, YEAR = {1993}, PAGES = {21--27}, ABSTRACT = {Bei dem Entwurf von Fuzzy--Controllern hat man bisher mit zwei entscheidenden Schwierigkeiten zu k\"ampfen. Zum einen ist dies das Tunen der charakterisierenden Zugeh\"origkeitsfunktionen, zum anderen ist es die Erstellung einer geeigneten Regelbasis.\\ In dieser Arbeit soll es um das Auffinden m\"oglichst optimaler Regeln --- der Grundlage eines Fuzzy--Controllers --- gehen. Expertenbefragung ist immer noch die g\"angige, jedoch zeitaufwendige und damit sehr teure Methode. Auch kann man sich nach dem Entwurf des Controllers nicht sicher sein, da\ss\ die Regelbasis ann\"ahernd optimal arbeitet. Diese Arbeit zeigt, wie sich die Entwicklungzeit von Fuzzy--Controllern mit Hilfe Genetischer Algorithmen wesentlich verk\"urzen l\"a\ss t und damit verbilligt und vor allem eine Regelbasis erzeugt wird, die einer optimalen L\"osung sehr nahe kommt.\\ An einer klassischen Regelungsaufgabe eines Fuzzy--Controllers wird die Erstellung des Genetischen Algorithmus verdeutlicht und die L\"osung dargestellt.\\ Es geht in dieser Arbeit also {\sl nicht} um das Tunen eines bestehenden Fuzzy--Controllers, sondern um die genetische Erzeugung der Regeln selbst ohne den Einsatz von Experten.}, } @MISC{Hopf94b, AUTHOR = {Hopf, J{\"o}rn}, TITLE = {Genetic Algorithms within the Framework of Evolutionary Computation}, HOWPUBLISHED = {In Proceedings of KI-94}, MONTH = {September}, YEAR = {1994}, PAGES = {2}, NOTE = {Preface of identical Workshop on KI-94, Saarbr{\"u}cken, Germany}, } @TECHREPORT{Hopf96a, EDITOR = {Claus, Volker and Hopf, J{\"o}rn and Schwefel, Hans-Paul}, TITLE = {Evolutionary Algorithms and their Application}, INSTITUTION = {IBFI}, TYPE = {Dagstuhl-Seminar-Report}, ADDRESS = {IBFI GmbH, Schloss Dagstuhl, D-66687 Wadern, Germany}, NUMBER = {140}, MONTH = {March}, ISBN = {0940-1121}, YEAR = {1996}, PAGES = {31}, } @TECHREPORT{Hopf96b, AUTHOR = {Hopf, J{\"o}rn}, EDITOR = {Claus, Volker and Hopf, J{\"o}rn and Schwefel, Hans-Paul}, TITLE = {Optimizing Photo Mask Layout for Grey-tone Lithography}, INSTITUTION = {IBFI}, TYPE = {Dagstuhl-Seminar-Report}, ADDRESS = {IBFI GmbH, Schloss Dagstuhl, D-66687 Wadern, Germany}, NUMBER = {140}, MONTH = {March}, ISBN = {0940-1121}, YEAR = {1996}, PAGES = {1}, } @TECHREPORT{Hopf96b, AUTHOR = {Hopf, J{\"o}rn}, EDITOR = {Claus, Volker and Hopf, J{\"o}rn and Schwefel, Hans-Paul}, TITLE = {Optimizing Photo Mask Layout for Grey-tone Lithography}, INSTITUTION = {IBFI}, TYPE = {Dagstuhl-Seminar-Report}, ADDRESS = {IBFI GmbH, Schloss Dagstuhl, D-66687 Wadern, Germany}, NUMBER = {140}, MONTH = {March}, ISBN = {0940-1121}, YEAR = {1996}, PAGES = {1}, } @INPROCEEDINGS{Hopf96c, AUTHOR = {Hopf, J{\"o}rn and Rau, Rainer}, EDITOR = {Jamshidi, Mohammad and Fathi, Madjid and Pierrot, Francois}, TITLE = {Decision Making in an Economy Exploiting Fuzzy Rules Obtained from a Genetic Algorithm}, BOOKTITLE = {Soft Computing with Industrial Applications}, ORGANIZATION = {World Automation Congress (WAC)}, PADDRESS = {Albuquerque, USA}, ADDRESS = {Montpellier, France}, PUBLISHER = {TSI Press}, MONTH = {May}, VOLUME = {5}, ISBN = {1-889335-02-9}, YEAR = {1996}, PAGES = {331--336}, ABSTRACT = {This paper describes the development of a fuzzy controller for a cybernetic system with emphasis on the generation of the required knowledge base. A cybernetic system in this context means a dynamic system consisting of several domains that interfere with each other. Despite the fact that the overall situation in the system results from the situations in {\sl all} the domains, it can only be influenced from the outside through {\sl some} domains. The actions that can be performed are also restricted. The algorithm does not require or use any knowledge of the meaning of the domains that would enable any ranking. Based on the model of a cybernetic game called ``\"Okolopoly'', it will be shown that it is possible to generate the rule base of a fuzzy controller without encoding previously gained knowledge, but simply with the help of a genetic algorithm.}, } @INPROCEEDINGS{Hopf97a, AUTHOR = {Hopf, J{\"o}rn}, EDITOR = {Steele, N.}, TITLE = {Cooperative Coevolution of Fuzzy Rules}, BOOKTITLE = {Proceedings of the 2nd International ICSC Symposium on Fuzzy Logic and Applications (ISFL-97)}, ORGANIZATION = {International Computer Science Conventions (ICSC)}, PADDRESS = {Millet, Alberta, Canada}, ADDRESS = {Zurich, Switzerland}, PUBLISHER = {ICSC Academic Press}, MONTH = {February}, ISBN = {3-906454-03-7}, YEAR = {1997}, PAGES = {337--381}, ABSTRACT = {This work introduces a new abstract scalable test function for the development of fuzzy rules and compares an evolutionary and a cooperative coevolutionary approach on it.}, } @PHDTHESIS{HopfDiss2001, AUTHOR = {Hopf, J{\"o}rn}, TITLE = {{Photomaskenlayout f{\"u}r eine 3D-Grauton-Lithographie als kombinatorisches Optimierungsproblem}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {June}, YEAR = {2001}, ABSTRACT = {{\scriptsize With this work it is developed the optimization of photo mask layout for silicon micro machining. Silicon micro machining could use equipment and processes of IC-technology (photo lithography and dry-etching) to produce micro mechanical systems and highly miniaturized three-dimensional micro structures on silicon like sensors, actuators and lenses. In particular the problem of laying out an appropriate photo mask under consideration of several production constraints is solved}.\\ Mit dieser Arbeit wurde die Optimierung von Photomasken f{\"u}r die Grautonlithographie zum Einsatz in der Mikrotechnologie entwickelt. Die Mikrotechnologie ist so in der Lage, Prozesse der Chipherstellung (Photolithographie und {\"A}tzprozesse) zu nutzen, um mikromechanische Systeme und dreidimensionale Mikrostrukturierung auf Silikon zu fertigen, wie beispielsweise Sensoren, Aktuatoren und Linsen. Speziell das Problem der Photomaskenoptimierung unter Ber{\"u}cksichtigung der produktionsbedingten und physikalischen Constraints konnte gel{\"o}st werden.\\ Gegeben ist eine gew{\"u}nschte Oberfl{\"a}chenfunktion $f(x,y)$ und die Menge ${\bf M}=\{m_1,\dots,m_n\}$, $n\in \Bbb{N}$, aller m{\"o}glichen Maskenelement e. Gesucht ist die Menge ${\bf M^*} \subset {\bf M}$, deren Anordnung und Geometrie den produktionsbedingten und physikalischen Constraints gen{\"u}gen m{\"u}ssen, und die die beste Approximation $g^*(x,y)=\sum_{m_i\in{\bf M}^*} G_i(x,y)$ an $f(x,y)$ liefert, wobei $G_i(x,y)$ den Grauwert repr{\"a}sentiert, den das Maskenelement $m_i$ an der Stelle $(x,y)$ erzeugt. Da die Berechnung der zu verwendenden Maskenelemente f{\"u}r eine optimale Approximation {\"u}ber die Funktion $g^*(x,y)$ analytisch nicht m{\"o}glich ist, mu{\ss}te ein Verfahren entwickelt werden, das eine Approximation von $g(x,y)=\sum_{m_i\in{\bf M}'} G_i(x,y)$ an $f(x,y)$ erm{\"o}glicht, wobei auch ${\bf M'} \subset {\bf M}$ ist.\\ Selbst f{\"u}r komplexe Oberfl{\"a}chenstrukturen, wie Fresnellinsen, ist es m{\"o}glich, mit nur einer Photomaske und einer kleinsten Kantenl{\"a}nge der Maskenelemente von ca.\ $0.7\mu{\rm m}$ im Rahmen der physikalischen M{\"o}glichkeiten eine Oberfl{\"a}chenapproximation von unter 2\% Abweichung an den jeweiligen Me{\ss}stellen und ebenfalls eine Oberfl{\"a}chenrauhigkeit im entsprechenden Integrationsradius von unter 2\% zu erzielen. Daraus resultiert bei beispielsweise $16\mu{\rm m}$ Strukturh{\"o}he eine Approximationsungenauigkeit von $<320 {\rm \mbox{nm}}$, was in der Regel bereits unterhalb der verwendeten Lichtwellenl{\"a}nge liegt.}, } @INPROCEEDINGS{HPT02, AUTHOR = {Hillenbrand, Thomas and Podelski, Andreas and Topi{\'c}, Dalibor}, EDITOR = {Charatonik, Witold and Ganzinger, Harald}, TITLE = {Is Logic Effective for Analyzing {C} Programs?}, BOOKTITLE = {Symposium on the Effectiveness of Logic in Computer Science in Honour of Moshe Vardi}, PADDRESS = {Saarbr{\"u}cken, Germany}, ADDRESS = {Saarbr{\"u}cken}, PUBLISHER = {Max-Planck-Institut f{\"u}r Informatik}, MONTH = {March}, SERIES = {MPI Research Report}, VOLUME = {MPI-I-2002-2-007}, YEAR = {2002}, PAGES = {27--30}, } @INPROCEEDINGS{HSW1998, AUTHOR = {Hustadt, Ullrich and Schmidt, Renate A. and Weidenbach, Christoph}, EDITOR = {de Swart, Harrie}, TITLE = {Optimised Functional Translation and Resolution}, BOOKTITLE = {Proceedings of the International Conference on Automated Reaso ning with Analytic Tableaux and Related Methods (TABLEAUX'98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Oisterwijk, The Netherlands}, PUBLISHER = {Springer}, MONTH = {May}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1397}, ISBN = {3-540-64406-7}, YEAR = {1998}, PAGES = {36--37}, } @PHDTHESIS{Hustadt1999, AUTHOR = {Hustadt, Ullrich}, TITLE = {Resolution-Based Decision Procedures for Subclasses of First-Order Logic}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {March}, YEAR = {1999}, ABSTRACT = {This thesis studies decidable fragments of first-order logic which are relevant to the field of non-classical logic and knowledge representation. We show that refinements of resolution based on suitable liftable orderings provide decision procedures for the subclasses $\CE^+$, $\overline{\mathrm{K}}$, and $\overline{\mathrm{DK}}$ of first-order logic. By the use of semantics-based translation methods we can embed the description logic $\mathcal{ALCR}$ and extensions of the basic modal logic $\mathsf{K}$ into fragments of first-order logic. We describe various decision procedures based on ordering refinements and selection functions for these fragments and show that a polynomial simulation of tableaux-based decision procedures for these logics is possible. In the final part of the thesis we develop a benchmark suite and perform an empirical analysis of various modal theorem provers.}, } @INCOLLECTION{Hustadt2001handbook, AUTHOR = {Ferm{\"u}ller, Christian G. and Leitsch, Alexander and Hustadt, Ullrich and Tammet, Tanel}, EDITOR = {Robinson, Alan and Voronkov, Andrei}, TITLE = {Resolution Decision Procedures}, BOOKTITLE = {Handbook of Automated Reasoning}, CHAPTER = {25}, ADDRESS = {Amsterdam, the Netherlands}, PUBLISHER = {Elsevier}, MONTH = {January}, VOLUME = {1}, YEAR = {2001}, PAGES = {1793--1849}, } @INPROCEEDINGS{Hustadt93a, AUTHOR = {Hustadt, Ullrich}, EDITOR = {Codognet, P. and Dung, P. M. and Kakas, A. C. and Mancarella, P.}, TITLE = {Abductive Disjunctive Logic Programming}, BOOKTITLE = {ICLP '93 Postconference Workshop on Abductive Reasoning}, PADDRESS = {Cambridge, USA}, ADDRESS = {Budapest, Hungary}, PUBLISHER = {MIT Press}, YEAR = {1993}, ABSTRACT = {Eshghi and Kowalski (1989) introduced the notion of an abductive framework and proposed stable models as a semantics for abduction. They showed that abductive frameworks can be used to provide an alternative basis for negation-as-failure in logic programming. Kakas and Mancarella (1990) introduced the notion of generalized stable models by suitably extending the definition of stable models. The semantics of generalized stable models clarifies the meaning of integrity constraints within an abductive framework. In (Satoh and Iwayama, 1992) a goal-directed method for computing the generalized stable models of an abductive framework has been proposed. Their method is correct for any consistent abductive framework. Whereas abductive frameworks correspond to normal logic programs with integrity constraints, I propose an extension to disjunctive normal logic programs. Disjunctive normal logic programs extend normal logic programs to disjunctive logic programs and therefore, provide full first-order expressibility.}, } @INPROCEEDINGS{Hustadt93b, AUTHOR = {Hustadt, Ullrich}, EDITOR = {B{\"u}rckert, Hans-J{\"u}rgen and Nutt, Werner}, TITLE = {Automated Support for the Development of Non-classical Logics}, BOOKTITLE = {Workshop: Modellierung epistemischer Propositionen, KI '93}, PADDRESS = {Berlin}, YEAR = {1993}, NOTE = {To appear as Research Report of DFKI}, ABSTRACT = {The most natural means for specifying a non-classical logic is by means of a Hilbert calculus. Usually, the semantics of a non-classical logic is given in terms of possible worlds. Given an axiomatization of a non-classical logics, the {\em correspondence problem} in these logics is to find for every given Hilbert axiom an equivalent property of the accessibility relation (van Benthem (1984)). For mechanizing deduction in non-classical logics it is very important to find these correspondences (Ohlbach (1991)). So far the method for finding the correspondences was mostly by intuition and the verification required complex proofs (van Benthem (1984)). SCAN is an algorithm which offers a method for computing the correspondences fully automatically. Moreover, since SCAN preserves equivalences, the computed correspondence axioms are {\em guaranteed to be complete} in the sense that a formula is derivable in the Hilbert calculus if and only if it is valid in the frames which are models of the computed correspondence axiom. In this paper we present the SCAN algorithm and an application of it to the problem of collapsing modalities in multi-modal logics: Given a Hilbert calculus for modalities $\Box_{m_1}$ and $\Box_{m_2}$ we have to ensure that $$\Box_{m_1} P \Leftrightarrow \Box_{m_2} P$$ doesn't hold for all formulae $P$, because this is in general an unwanted consequence of the given axiomatization.}, } @INPROCEEDINGS{Hustadt93c, AUTHOR = {Hustadt, Ullrich and Nonnengart, Andreas}, EDITOR = {Rowles, C. and Liu, H. and Foo, N.}, TITLE = {Modalities in Knowledge Representation}, BOOKTITLE = {Proc. of the 6th Australian Joint Conference on Artificial Intelligence (AI '93)}, PADDRESS = {Singapore}, ADDRESS = {Melbourne, Australia}, PUBLISHER = {World Scientific}, YEAR = {1993}, PAGES = {249--254}, ABSTRACT = {Standard knowledge representation systems are supposed to be able to represent either common or individual knowledge about the world. In this paper we propose an extension to such knowledge representation systems which, in a uniform manner, allows to express beliefs of multiple agents as well as knowledge, desire, time and in fact any modality which has a first-order predicate logic possible world semantics.}, } @INPROCEEDINGS{Hustadt94b, AUTHOR = {Hustadt, Ullrich}, EDITOR = {Laux, Arnim and Wansing, Heinrich}, TITLE = {Common and Mutual Belief for Agent Modeling}, BOOKTITLE = {Modeling Epistemic Propositions: Workshop during the 18th German Annual Conference on Artificial Intelligence (KI-94)}, ADDRESS = {Saarbr{\"u}cken, Germany}, YEAR = {1994}, NOTE = {To appear in `Knowledge and Belief in Philosophy and Artificial Intelligence', Akademie-Verlag, Berlin, 1995}, ABSTRACT = {We want to consider a dialog situation between a system and a heterogeneous group of dialog partners. Our problem is to find adequate representational means for describing the beliefs, goals, and plans of each agent. We assume that we can provide a sufficiently detailed description of the knowledge base of the system, but we don't have complete descriptions of the knowledge bases of all other participating agents. In this paper I propose an approach which is in line with the {\em modal logic approach\/} of Allgayer, Ohlbach, and Reddig (1992). The basic idea is to enhance a decidable fragment of first-order logic with modal operators for modeling the notions of belief, knowledge, and desires. To provide the initial knowledge base for agents, we support mutual and group beliefs, knowledge, and desires.}, } @INPROCEEDINGS{Hustadt94b2, AUTHOR = {Hustadt, Ullrich}, EDITOR = {Kunze, J{\"u}rgen and Stoyan, Herbert}, TITLE = {Common and Mutual Belief for Agent Modeling}, BOOKTITLE = {{KI-94} Workshops: Extended Abstracts}, PADDRESS = {Bonn, Germany}, ADDRESS = {Saarbr{\"u}cken, Germany}, PUBLISHER = {Gesellschaft f{\"u}r Informatik}, MONTH = {September}, YEAR = {1994}, PAGES = {123--124}, } @INPROCEEDINGS{Hustadt94c, AUTHOR = {Hustadt, Ullrich}, EDITOR = {Baader, Franz and Buchheit, Martin and Jeusfeld, Manfred A. and Nutt, Werner}, TITLE = {Do we need the closed-world assumption in knowledge representation?}, BOOKTITLE = {Working Notes of the KI'94 Workshop: Reasoning about Structured Objects: Knowledge Representation meets Databases (KRDB'94)}, PADDRESS = {Saarbr{\"u}cken, Germany}, ADDRESS = {Saarbr{\"u}cken, Germany}, PUBLISHER = {DFKI}, MONTH = {November}, SERIES = {Document}, VOLUME = {D-94-11}, YEAR = {1994}, PAGES = {24--26}, ABSTRACT = {In this paper I want to focus on some principal differences between data models of database systems and knowledge representation languages. The data manipulation languages of data models are based on the closed-world, unique-name, and domain-closure assumption. Data manipulation languages and query languages of knowledge representation formalisms differ considerably in their underlying assumptions. They are based on the open-world, unique-name, and open-domain assumption. That means, that even if the data definition language and the data manipulation language of a database management system and a knowledge base management system would coincide, the results of data manipulations would differ. I present some examples that show the usefulness of closed-world inferences in natural language processing. Thus knowledge representation languages sticking to the open-world assumption seem to be insufficient for natural language processing.}, } @INPROCEEDINGS{Hustadt94c2, AUTHOR = {Hustadt, Ullrich}, EDITOR = {Kunze, J{\"u}rgen and Stoyan, Herbert}, TITLE = {Do we need the closed-world assumption in knowledge representation?}, BOOKTITLE = {{KI-94} Workshops: Extended Abstracts}, PADDRESS = {Bonn, Germany}, ADDRESS = {Saarbr{\"u}cken, Germany}, PUBLISHER = {Gesellschaft f{\"u}r Informatik}, MONTH = {September}, YEAR = {1994}, PAGES = {293--294}, } @INPROCEEDINGS{Hustadt94d, AUTHOR = {Hustadt, Ullrich}, TITLE = {A Multi-Modal Logic for Stereotyping}, BOOKTITLE = {Proceedings of the 4th International Conference on User Modeling {UM94}}, PADDRESS = {Bedford, USA}, ADDRESS = {Hyannis, MA}, PUBLISHER = {The MITRE Corporation}, MONTH = {August}, YEAR = {1994}, PAGES = {87--92}, NOTE = {Order copies from: Bradley A. Goodman, The MITRE Corporation, Artificial Intelligence Center, 202 Burlingtom Road, Bedford, MA 01730-1420, USA}, ABSTRACT = {In a mixed-initiative dialogue between multiple interlocutors, the ability to construct, to maintain, and to exploit an explicit model of the dialogue partners' beliefs, goals, and plans is indispensable. An {\em agent model\/} is required for identifying the objects which the dialogue partner is talking about, for planning the appropriate dialogue contributions towards achieving the own goals, and for determining the effects of planned dialogue contributions on the dialogue partner. If we assume that we have no access to existing models of the dialogue partners, then we have to solve the problem of constructing the initial agent model at the beginning of the dialogue. The approach I propose here is in line with the {\em modal logic approach\/} to agent and stereotype modeling of Allgayer, Ohlbach, and Reddig (1992). The basic idea is to enhance a decidable fragment of first-order logic with modal operators modeling the notions of belief, knowledge, and desire. To provide reasoning capabilities we follow the translation approach of Nonnengart (1992). This amounts to manipulating modal logic formulas by a certain set of transformation rules so that classical, i.e.\ first-order, proof methods can be applied.}, } @INCOLLECTION{Hustadt95b, AUTHOR = {Hustadt, Ullrich}, EDITOR = {Laux, Arnim and Wansing, Heinrich}, TITLE = {Introducing Epistemic Operators into a Description Logic}, BOOKTITLE = {Knowledge and Belief in Philosophie and Artificial Intelligence}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Akademie Verlag}, SERIES = {Logica Nova}, ISBN = {3-05-002791-6}, YEAR = {1995}, PAGES = {65--85}, ABSTRACT = {We want to consider a dialog situation between a system and a heterogeneous group of dialog partners. Our problem is to find adequate representational means for describing the beliefs, goals, and plans of each agent. We assume that we can provide a sufficiently detailed description of the knowledge base of the system, but we don't have complete descriptions of the knowledge bases of all other participating agents. In this paper I propose an approach which is in line with the {\em modal logic approach\/} of Allgayer, Ohlbach, and Reddig (1992). The basic idea is to enhance a decidable fragment of first-order logic with modal operators for modeling the notions of belief, knowledge, and desires. To provide the initial knowledge base for agents, we support mutual and group beliefs, knowledge, and desires.}, } @INPROCEEDINGS{HustadtSchmidt97b, AUTHOR = {Hustadt, Ullrich and Schmidt, Renate A.}, EDITOR = {Pollack, Martha E.}, TITLE = {On Evaluating Decision Procedures for Modal Logics}, BOOKTITLE = {Proceedings of the Fifteenth International Joint Conference on Artificial Intelligence (IJCAI-97)}, ORGANIZATION = {International Joint Conferences on Artificial Intelligence, Inc. (IJCAII) and Japanese Society for Artificial Intelligence (JSAI)}, PADDRESS = {San Francisco, USA}, ADDRESS = {Nagoya, Japan}, PUBLISHER = {Morgan Kaufmann}, ISBN = {1-55860-480-4}, YEAR = {1997}, PAGES = {202--207}, ABSTRACT = {This paper investigates the evaluation method of decision procedures for multi-modal logic proposed by Giunchiglia and Sebastiani as an adaptation from the evaluation method of Mitchell et al.\ of decision procedures for propositional logic. We compare three different theorem proving approaches, namely, the Davis-Putnam-based procedure K\textsc{sat}, the tableaux-based system $\mathcal{KRIS} and a translation approach combined with first-order resolution. Our results do not support the claims of Giunchiglia and Sebastiani concerning the computational superiority of K\textsc{sat} over $\mathcal{KRIS}$, and an easy-hard-easy pattern for randomly generated modal formulae.}, } @INPROCEEDINGS{HustadtSchmidt98a, AUTHOR = {Hustadt, Ullrich and Schmidt, Renate A.}, EDITOR = {de Swart, Harrie}, TITLE = {Simplification and backjumping in modal tableau}, BOOKTITLE = {Proceedings of the International Conference on Automated Reaso ning with Analytic Tableaux and Related Methods (TABLEAUX'98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Oisterwijk, The Netherlands}, PUBLISHER = {Springer}, MONTH = {May}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1397}, ISBN = {3-540-64406-7}, YEAR = {1998}, PAGES = {187--201}, ABSTRACT = {This paper is concerned with various schemes for enhancing the performance of modal tableau procedures. It discusses techniques and strategies for dealing with the nondeterminism in tableau calculi, as well as simplification and backjumping. Benchmark results obtained with randomly generated modal formulae show the effect of combinations of different schemes.}, } @INPROCEEDINGS{HustadtSchmidt99a, AUTHOR = {Hustadt, Ullrich and Schmidt, Renate A.}, EDITOR = {Ganzinger, Harald}, TITLE = {Maslov's Class {K} Revisited}, BOOKTITLE = {Proceedings of the 16th International Conference on Automated Deduction (CADE-16)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Trento, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1632}, ISBN = {3-540-66222-7}, YEAR = {1999}, PAGES = {172--186}, ABSTRACT = {This paper gives a new treatment of Maslov's class $\mathrm{K}$ in the framework of resolution. More specifically, we show that $\mathrm{K}$ and the class $\mathrm{DK}$ consisting of disjunction of formulae in $\mathrm{K}$ can be decided by a resolution refinement based on liftable orderings. We also discuss relationships to other solvable and unsolvable classes.}, } @INPROCEEDINGS{HustadtSchmidt99b, AUTHOR = {Hustadt, Ullrich and Schmidt, Renate A.}, TITLE = {On the relation of resolution and tableaux proof systems for description logics}, BOOKTITLE = {Proceedings of the 16th International Joint Conference on Artificial Intelligence (IJCAI-99)}, ORGANIZATION = {International Joint Conference on Artificial Intelligence, Inc., The Scandanavian AI Societies}, PADDRESS = {San Francisco, USA}, ADDRESS = {Stockholm, Sweden}, PUBLISHER = {Morgan Kaufmann}, VOLUME = {1}, ISBN = {1-55860-613-0}, YEAR = {1999}, PAGES = {110--115}, ABSTRACT = {This paper investigates the relationship between resolution and tableaux proof system for the satisfiability of general knowledge bases in the description logic $\mathcal{ALC}$. We show that resolution proof systems can polynomially simulate their tableaux counterpart. Our resolution proof system is based on a selection refinement and utilises standard redundancy elimination criteria to ensure termination.}, } @ARTICLE{HustadtSchmidt99e, AUTHOR = {Hustadt, Ullrich and Schmidt, Renate A.}, JOURNAL = {Journal of Applied Non-Classical Logics}, TITLE = {An Empirical Analysis of Modal Theorem Provers}, ADDRESS = {Paris, France}, NUMBER = {4}, PUBLISHER = {Hermes}, VOLUME = {9}, YEAR = {1999}, PAGES = {479--522}, ABSTRACT = {This paper reports on an empirical performance analysis of four modal theorem provers on benchmark suites of randomly generated formulae. The theorem provers tested are the Davis-Putnam-based procedure KSAT, the tableaux-based system KRIS, the sequent-based Logics Workbench, and a translation approach combined with the first-order theorem prover SPASS. Our benchmark suites are sets of multi-modal formulae in a certain normal form randomly generated according to the scheme of Giunchiglia and Sebastiani~[CADE96,KR96]. We investigate the quality of the random modal formulae and show that the scheme has some shortcomings, which may lead to mistaken conclusions. We propose improvements to the evaluation method and show that the translation approach provides a viable alternative to the other approaches.}, } @PROCEEDINGS{ICTL94, EDITOR = {Gabbay, Dov M. and Ohlbach, Hans J{\"u}rgen}, TITLE = {Temporal Logic: Proceedings of the 1st International Conference on Temporal Logic}, PADDRESS = {Berlin, Germany}, ADDRESS = {Bonn, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {827}, ISBN = {3-540-58241}, YEAR = {1994}, PAGES = {546}, } @INPROCEEDINGS{jacobs-sofronie-pdpar-06, AUTHOR = {Jacobs, Swen and Sofronie-Stokkermans, Viorica}, EDITOR = {Cook, Byron and Sebastiani, Roberto}, TITLE = {Applications of hierarchical reasoning in the verification of complex systems}, BOOKTITLE = {PDPAR'06: Pragmatical Aspects of Decision Procedures in Automated Reasoning}, PADDRESS = {-}, ADDRESS = {Seattle, USA}, PUBLISHER = {-}, MONTH = {August}, YEAR = {2006}, PAGES = {15--26}, ABSTRACT = {In this paper we show how hierarchical reasoning can be used to verify properties of complex systems. Chains of local theory extensions are used to model a case study taken from the European Train Control System (ETCS) standard, but considerably simplified. We show how testing invariants and bounded model checking can automatically be reduced to checking satisfiability of ground formulae over a base theory.}, } @ARTICLE{jacobs-sofronie-pdpar-entcs, AUTHOR = {Jacobs, Swen and Sofronie-Stokkermans, Viorica}, JOURNAL = {Electronic Notes in Theoretical Computer Science}, TITLE = {Applications of hierarchical reasoning in the verification of complex systems}, PUBLISHER = {Elsevier}, ISBN = {1571-0661}, YEAR = {2007}, ABSTRACT = {In this paper we show how hierarchical reasoning can be used to verify properties of complex systems. Chains of local theory extensions are used to model a case study taken from the European Train Control System (ETCS) standard, but considerably simplified. We show how testing invariants and bounded model checking (for safety properties expressed by universally quantified formulae, depending on certain parameters of the systems) can automatically be reduced to checking satisfiability of ground formulae over a base theory. }, } @MASTERSTHESIS{Jacobs2004, AUTHOR = {Jacobs, Swen}, TITLE = {Instance Generation Methods for Automated Reasoning}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {October}, YEAR = {2004}, ABSTRACT = {There are several different methods which try to decide unsatisfiability of a set of clauses by generating an unsatisfiable set of instances of the input clauses. We consider the \emph{Disconnection Tableau Calculus}, \emph{Primal Partial Instantiation} and \emph{Resolution-Based Instance-Generation}, all of which can be seen as refinements of the clause linking approach. We present these three methods accurately and in a consistent manner. Similarities and equivalences of the methods will be pointed out and we will show if proofs of one calculus can be simulated by a different method, generating only instances from the given proof.}, } @INPROCEEDINGS{JacobsWaldmann2005, AUTHOR = {Jacobs, Swen and Waldmann, Uwe}, EDITOR = {Beckert, Bernhard}, TITLE = {Comparing Instance Generation Methods for Automated Reasoning}, BOOKTITLE = {Automated reasoning with analytic tableaux and related methods : International Conference, TABLEAUX 2005}, PADDRESS = {Berlin, Germany}, ADDRESS = {Koblenz, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3702}, ISBN = {3-540-28931-3}, YEAR = {2005}, PAGES = {153--168}, ABSTRACT = {The clause linking technique of Lee and Plaisted proves the unsatisfiability of a set of first-order clauses by generating a sufficiently large set of instances of these clauses that can be shown to be propositionally unsatisfiable. In recent years, this approach has been refined in several directions, leading to both tableau-based methods, such as the Disconnection Tableau Calculus, and saturation-based methods, such as Primal Partial Instantiation and Resolution-based Instance Generation. We investigate the relationship between these calculi and answer the question to what extent refutation or consistency proofs in one calculus can be simulated in another one.}, } @INPROCEEDINGS{JacquemardMeyerWeidenbach98, AUTHOR = {Jacquemard, Florent and Meyer, Christoph and Weidenbach, Christoph}, EDITOR = {Nipkow, Tobias}, TITLE = {Unification in Extensions of Shallow Equational Theories}, BOOKTITLE = {Proceedings of the 9th International Conference on Rewriting Techniques and Applications (RTA-98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Tsukuba, Japan}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1379}, ISBN = {3-540-64301-X}, YEAR = {1998}, PAGES = {76--90}, ABSTRACT = {We show that unification in certain extensions of shallow equational theories is decidable. Our extensions generalize the known classes of shallow or standard equational theories. In order to prove decidability of unification in the extensions, a class of Horn clause sets called sorted shallow equational theories is introduced. This class is a natural extension of tree automata with equality constraints between brother subterms as well as shallow sort theories. We show that saturation under sorted superposition is effective on sorted shallow equational theories. So called semi-linear equational theories can be effectively transformed into equivalent sorted shallow equational theories and generalize the classes of shallow and standard equational theories. }, } @ARTICLE{Jaeger00, AUTHOR = {Jaeger, Manfred}, JOURNAL = {Artificial Intelligence}, TITLE = {On the complexity of inference about probabilistic relational models}, ADDRESS = {Amsterdam, the Netherlands}, PUBLISHER = {Elsevier}, VOLUME = {117}, ISBN = {0004-3702}, YEAR = {2000}, PAGES = {297--308}, ABSTRACT = {We investigate the complexity of probabilistic inference from knowledge bases that encode probability distributions on finite domain relational structures. Our interest here lies in the complexity in terms of the domain under consideration in a specific application instance. We obtain the result that assuming NETIME$\neq$ETIME this problem is not polynomial for reasonably expressive representation systems. The main consequence of this result is that it is unlikely to find inference techniques with a better worst-case behavior than the commonly employed strategy of constructing standard Bayesian networks over ground atoms (knowledge based model construction). }, } @INPROCEEDINGS{Jaeger1998a, AUTHOR = {Jaeger, Manfred}, EDITOR = {Cohn, Anthony G. and Schubert, Lenhart and Shapiro, Stuart C.}, TITLE = {Reasoning About Infinite Random Structures with Relational Bayesian Networks}, BOOKTITLE = {Proceedings of the 6th International Conference on Principles of Knowledge Representation and Reasoning (KR-98)}, PADDRESS = {San Francisco, USA}, ADDRESS = {Trento, Italy}, PUBLISHER = {Morgan Kaufmann}, ISBN = {1-55860-554-1}, YEAR = {1998}, PAGES = {570--581}, ABSTRACT = {Relational Bayesian networks extend standard Bayesian networks by integrating some of the expressive power of first-order logic into the Bayesian network paradigm. As in the case of the related technique of knowledge based model construction, so far, decidable semantics only have been provided for finite stochastic domains. In this paper we extend the semantics of relational Bayesian networks, so that they also define probability distributions over countably infinite structures. Using a technique remeniscent of quantifier elimination methods in model theory, we show that probabilistic queries about these distributions are decidable. }, } @INPROCEEDINGS{Jaeger1998b, AUTHOR = {Jaeger, Manfred}, EDITOR = {Pratt, Vaughan}, TITLE = {Convergence Results for Relational {Bayesian} Networks}, BOOKTITLE = {Proceedings of the 13th Annual IEEE Symposium on Logic in Computer Science (LICS-98)}, ORGANIZATION = {IEEE Technical Committee on Mathematical Foundations of Computing}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Indianapolis, USA}, PUBLISHER = {IEEE}, YEAR = {1998}, PAGES = {44--55}, ABSTRACT = {Relational Bayesian networks are an extension of the method of probabilistic model construction by Bayesian networks. They define probability distributions on finite relational structures by conditioning the probability of a ground atom $r(a_1,\ldots,a_n)$\ on first-order properties of $a_1,\ldots,a_n$\ that have been established by previous random decisions. In this paper we investigate from a finite model theory perspective the convergence properties of the distributions defined in this manner. A subclass of relational Bayesian networks is identified that define distributions with convergence laws for first-order properties. }, } @INPROCEEDINGS{Jaeger1998c, AUTHOR = {Jaeger, Manfred}, EDITOR = {Cooper, Gregory S. and Moral, Seraf{\'i}n}, TITLE = {Measure Selection: Notions of Rationality and Representation Independence}, BOOKTITLE = {Proceedings of the 14th Conference on Uncertainty in Artificial Intelligence (UAI-98)}, PADDRESS = {San Francisco, USA}, ADDRESS = {Madison, USA}, PUBLISHER = {Morgan Kaufmann}, YEAR = {1998}, PAGES = {274--281}, ABSTRACT = {We take another look at the general problem of selecting a preferred probability measure among those that comply with some given constraints. The dominant role that entropy maximization has obtained in this context is questioned by arguing that the minimum information principle on which it is based could be supplanted by an at least as plausible ``likelihood of evidence'' principle. We then review a method for turning given selection functions into representation independent variants, and discuss the tradeoffs involved in this transformation.}, } @ARTICLE{Jaeger93a, AUTHOR = {Jaeger, Manfred}, JOURNAL = {Artificial Intelligence}, TITLE = {Circumscription: Completeness Reviewed}, VOLUME = {60}, YEAR = {1993}, PAGES = {293--301}, ABSTRACT = {In this paper we demonstrate that some results on the completeness of {\it P}-defining theories published earlier are incorrect. We point out that by restricting the original propositions to well-founded theories results somewhat weaker than the original ones can be retained. We also present a theorem that provides some insight into the relation between completeness and reducibility and helps to identify the theories whose minimal models can be adequately handled with circumscription.}, } @INPROCEEDINGS{Jaeger94a, AUTHOR = {Jaeger, Manfred}, EDITOR = {Doyle, J. and Sandewall, E. and Torasso, P.}, TITLE = {Probabilistic Reasoning in Terminological Logics}, BOOKTITLE = {Principles of Knowledge Representation an Reasoning: Proceedings of the 4th International Conference (KR94)}, PADDRESS = {San Mateo, CA}, ADDRESS = {Bonn, Germany}, PUBLISHER = {Morgan Kaufmann}, YEAR = {1994}, PAGES = {305--316}, ABSTRACT = {In this paper a probabilistic extensions for terminological knowledge representation languages is defined. Two kinds of probabilistic statements are introduced: statements about conditional probabilities between concepts and statements expressing uncertain knowledge about a specific object. The usual model-theoretic semantics for terminological logics are extended to define interpretations for the resulting probabilistic language. It is our main objective to find an adequate modelling of the way the two kinds of probabilistic knowledge are combined in commonsense inferences of probabilistic statements. Cross entropy minimization is a technique that turns out to be very well suited for achieving this end.}, } @INPROCEEDINGS{Jaeger94c, AUTHOR = {Jaeger, Manfred}, EDITOR = {Lopez de Mantaraz, Ramon and Poole, David}, TITLE = {A Logic for Default Reasoning About Probabilities}, BOOKTITLE = {Proceedings of the 10th Conference on Uncertainty in Artificial Intelligence (UAI'94)}, PADDRESS = {San Mateo, CA}, ADDRESS = {Seattle, USA}, PUBLISHER = {Morgan Kaufmann}, YEAR = {1994}, PAGES = {352--359}, ABSTRACT = {A logic is defined that allows to express information about statistical probabilities and about degrees of belief in specific propositions. By interpreting the two types of probabilities in one common probability space, the semantics given are well suited to model the influence of statistical information on the formation of subjective beliefs. Cross entropy minimization is a key element in these semantics, the use of which is justified by showing that the resulting logic exhibits some very reasonable properties.}}, } @INPROCEEDINGS{Jaeger95, AUTHOR = {Jaeger, Manfred}, EDITOR = {Mellish, Chris S.}, TITLE = {Minimum Cross-Entropy Reasoning: A Statistical Justification}, BOOKTITLE = {Proceedings of the Fourteenth International Joint Conference on Artificial Intelligence (IJCAI-95)}, PADDRESS = {San Francisco, USA}, ADDRESS = {Montr{\'e}al, Canada}, PUBLISHER = {Morgan Kaufmann}, YEAR = {1995}, PAGES = {1847--1852}, ABSTRACT = {Degrees of belief are formed using observed evidence and statistical background information. In this paper we examine the process of how prior degrees of belief derived from the evidence are combined with statistical data to form more specific degrees of belief. A statistical model for this process then is shown to vindicate the cross-entropy minimization principle as a rule for probabilistic default-inference.}, } @INPROCEEDINGS{Jaeger96KR, AUTHOR = {Jaeger, Manfred}, EDITOR = {Carlucci-Aiello, Luigia and Doyle, Jon and Shapiro, Stuart}, TITLE = {Representation Independence of Nonmonotonic Inference Relations}, BOOKTITLE = {Principles of Knowledge Representation and Reasoning, Proceedings of the 5th International Conference (KR-96)}, PADDRESS = {San Francisco, USA}, ADDRESS = {Cambridge, Massachusetts}, PUBLISHER = {Morgan Kaufmann}, ISBN = {1-55860-421-9}, YEAR = {1996}, PAGES = {461--472}, ABSTRACT = {A logical concept of representation independence is developed for nonmonotonic logics, including probabilistic inference systems. The general framework then is applied to several nonmonotonic logics, particularly propositional probabilistic logics. For these logics our investigation leads us to modified inference rules with greater representation independence. }, } @INPROCEEDINGS{Jaeger97UAI, AUTHOR = {Jaeger, Manfred}, EDITOR = {Geiger, Dan and Shenoy, Prakash Pundalik}, TITLE = {Relational Bayesian Networks}, BOOKTITLE = {Proceedings of the 13th Conference of Uncertainty in Artificial Intelligence (UAI-13)}, PADDRESS = {San Francisco, USA}, ADDRESS = {Providence, USA}, PUBLISHER = {Morgan Kaufmann}, ISBN = {1-55860-485-5}, YEAR = {1997}, PAGES = {266--273}, ABSTRACT = {A new method is developed to represent probabilistic relations on multiple random events. Where previously knowledge bases containing probabilistic rules were used for this purpose, here a probability distribution over the relations is directly represented by a Bayesian network. By using a powerful way of specifying conditional probability distributions in these networks, the resulting formalism is more expressive than the previous ones. Particularly, it provides for constraints on equalities of events, and it allows to define complex, nested combination functions. }, } @INPROCEEDINGS{Jaeger99, AUTHOR = {Jaeger, Manfred}, EDITOR = {Kwiatkowska, Marta}, TITLE = {Fairness, Computable Fairness and Randomness}, BOOKTITLE = {Proceedings of the 2nd International Workshop on Probabilistic Methods in Verification (PROBMIV-99)}, PADDRESS = {Birmingham}, ADDRESS = {Eindhoven, the Netherlands}, PUBLISHER = {School of Computer Science, University of Birmingham}, MONTH = {August}, SERIES = {Technical Report CSR-99-8}, YEAR = {1999}, PAGES = {57--66}, ABSTRACT = {Motivated by the observation that executions of a probabilistic system almost surely are fair, we interpret concepts of fairness for nondeterministic processes as partial descriptions of probabilistic behavior. We propose computable fairness as a very strong concept of fairness, attempting to capture all the qualitative properties of probabilistic behavior that we might reasonably expect to see in the behavior of a nondeterministic system. It is shown that computable fairness does describe probabilistic behavior by proving that runs of a probabilistic system almost surely are computable fair. We then turn to the question of how sharp an approximation of randomness is obtained by computable fairness by discussing completeness of computable fairness for certain classes of path properties.}, } @ARTICLE{JaegerAMAI01, AUTHOR = {Jaeger, Manfred}, JOURNAL = {Annals of Mathematics and Artificial Intelligence}, TITLE = {Complex Probabilistic Modeling with Recursive Relational Bayesian Networks}, ADDRESS = {Dordrecht, The Netherlands}, PUBLISHER = {Kluwer}, VOLUME = {32}, ISBN = {1012-2443}, YEAR = {2001}, PAGES = {179--220}, ABSTRACT = {A number of representation systems have been proposed that extend the purely propositional Bayesian network paradigm with representation tools for some types of first-order probabilistic dependencies. Examples of such systems are dynamic Bayesian networks and systems for knowledge based model construction. We can identify the representation of probabilistic relational models as a common well-defined semantic core of such systems. Recursive relational Bayesian networks (RRBNs) are a framework for the representation of probabilistic relational models. A main design goal for RRBNs is to achieve greatest possible expressiveness with as few elementary syntactic constructs as possible. The advantage of such an approach is that a system based on a small number of elementary constructs will be much more amenable to a thorough mathematical investigation of its semantic and algorithmic properties than a system based on a larger number of high-level constructs. In this paper we show that with RRBNs we have achieved our goal, by showing, first, how to solve within that framework a number of non-trivial representation problems. In the second part of the paper we show how to construct from a RRBN and a specific query, a standard Bayesian network in which the answer to the query can be computed with standard inference algorithms. Here the simplicity of the underlying representation framework greatly facilitates the development of simple algorithms and correctness proofs. As a result we obtain a construction algorithm that even for RRBNs that represent models for complex first-order and statistical dependencies generates standard Bayesian networks of size polynomial in the size of the domain given in a specific application instance.}, } @INPROCEEDINGS{JaegerECSQARU03, AUTHOR = {Jaeger, Manfred}, EDITOR = {Nielsen, Thomas D. and Zhang, Nevin L.}, TITLE = {A Representation Theorem and Applications}, BOOKTITLE = {Symbolic and Quantitative Approaches to Reasoning with Uncertainty : 7th European Conference, ECSQARU 2003}, PADDRESS = {Berlin, Germany}, ADDRESS = {Aalborg, Denmark}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2711}, ISBN = {3-540-40494-5}, YEAR = {2003}, PAGES = {50--61}, ABSTRACT = {We introduce a set of transformations on the set of all probability distributions over a finite state space, and show that these transformations are the only ones that preserve certain elementary probabilistic relationships. This result provides a new perspective on a variety of probabilistic inference problems in which invariance considerations play a role. Two particular applications we consider in this paper are the development of an equivariance-based approach to the problem of measure selection, and a new justification for Haldane's prior as the distribution that encodes prior ignorance about the parameter of a multinomial distribution. }, } @PHDTHESIS{JaegerHabil, AUTHOR = {Jaeger, Manfred}, TITLE = {Probabilistic Decision Graphs}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Habilitation thesis}, MONTH = {December}, YEAR = {2002}, NOTE = {Antrittsvorlesung, no publication.}, } @INPROCEEDINGS{JaegerICML03, AUTHOR = {Jaeger, Manfred}, EDITOR = {Fawcett, Tom and Mishra, Nina}, TITLE = {Probabilistic Classifiers and the Concepts they Recognize}, BOOKTITLE = {Proceedings of the Twentieth International Conference on Machine Learning (ICML-03)}, PADDRESS = {Menlo Park, USA}, ADDRESS = {Washington DC, U.S.}, PUBLISHER = {AAAI Press}, ISBN = {0-1-57735-189-4}, YEAR = {2003}, PAGES = {266--273}, ABSTRACT = {We investigate algebraic, logical, and geometric properties of concepts recognized by various classes of probabilistic classifiers. For this we introduce a natural hierarchy of probabilistic classifiers, the lowest level of which comprises the naive Bayesian classifiers. We show that the expressivity of classifiers on the different levels in the hierarchy is characterized algebraically by separability with polynomials of different degrees. A consequence of this result is that every linearly separable concept can be recognized by a naive Bayesian classifier. We contrast this result with negative results about the naive Bayesian classifier previously reported in the literature, and point out that these results only pertain to specific learning scenarios for naive Bayesian classifiers. We also present some logical and geometric characterizations of linearly separable concepts, thus providing additional intuitive insight into what concepts are recognizable by naive Bayesian classifiers. }, } @ARTICLE{JaegerIJAR01, AUTHOR = {Jaeger, Manfred}, JOURNAL = {International Journal of Approximate Reasoning}, TITLE = {Automatic Derivation of Probabilistic Inference Rules}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {1}, PUBLISHER = {Elsevier}, VOLUME = {28}, ISBN = {0888-613X}, YEAR = {2001}, PAGES = {1--22}, ABSTRACT = {A probabilistic inference rule is a general rule that provides bounds on a target probability given constraints on a number of input probabilities. Example: from $P(A | B) \leq r$\ infer $P(\neg A | B) \in [1-r,1]$. Rules of this kind have been studied extensively as a deduction method for propositional probabilistic logics. Many different rules have been proposed, and their validity proved -- often with substantial effort. Building on previous work by T. Hailperin, in this paper we show that probabilistic inference rules can be derived automatically, i.e. given the input constraints and the target probability, one can automatically derive the optimal bounds on the target probability as a functional expression in the parameters of the input constraints.}, } @INPROCEEDINGS{JaegerIJCAI01, AUTHOR = {Jaeger, Manfred}, EDITOR = {Nebel, Bernhard}, TITLE = {Constraints as Data: a New Perspective on Inferring Probabilities}, BOOKTITLE = {Proceedings of the 17th International Joint Conference on Artificial Intelligence (IJCAI-01)}, ORGANIZATION = {International Joint Conferences on Artificial Intelligence, Inc.}, PADDRESS = {San Francisco, USA}, ADDRESS = {Seattle, USA}, PUBLISHER = {Morgan Kaufmann}, ISBN = {1-55860-777-3}, YEAR = {2001}, PAGES = {755--760}, ABSTRACT = {We present a new approach to inferring a probability distribution which is incompletely specified by a number of linear constraints. We argue that the currently most popular approach of entropy maximization depends on a ``constraints as knowledge'' interpretation of the constraints, and that a different ``constraints as data'' perspective leads to a completely different type of inference procedures by statistical methods. With statistical methods some of the counterintuitive results of entropy maximization can be avoided, and inconsistent sets of constraints can be handled just like consistent ones. A particular statistical inference method is developed and shown to have a nice robustness property.}, } @ARTICLE{JaegerMI19, AUTHOR = {Jaeger, Manfred}, JOURNAL = {Electronic Transactions on Artificial Intelligence}, TITLE = {Relational Bayesian Networks: a Survey}, ADDRESS = {Link{\"o}ping, Sweden}, PUBLISHER = {Link{\"o}ping University Electronic Press}, VOLUME = {6}, ISBN = {1403-3526}, YEAR = {2002}, ABSTRACT = {We give an overview of the relational Bayesian network modeling language. First the semantic concept of a random relational structure model is introduced, and then it is shown how such models can be represented with relational Bayesian networks. We consider a number of inference problems for relational Bayesian networks that range from elementary probabilistic queries to the computation of limit probabilities and learning problems. For some of these inference problems fully developed solution algorithms are available, for others we describe solution strategies by reduction to well-established logical inference and numerical optimization problems. }, } @INPROCEEDINGS{JaegerPGM02, AUTHOR = {Jaeger, Manfred}, TITLE = {Probababilistic Decision Graphs - Combining Verification and AI Techniques for Probabilistic Inference}, BOOKTITLE = {Proceedings of the First European Workshop on Probabilistic Graphical Models}, PADDRESS = {-}, ADDRESS = {Cuenca, Spain}, PUBLISHER = {Computer Science Department, University of Castilla - La Mancha}, MONTH = {November}, YEAR = {2002}, PAGES = {81--88}, ABSTRACT = {We adopt probabilistic decision graphs developed in the field of automated verification as a tool for probabilistic model representation and inference. We show that probabilistic inference has linear time complexity in the size of the probabilistic decision graph, that the smallest probabilistic decision graph for a given distribution is at most as large as the smallest junction tree for the same distribution, and that in some cases it can in fact be much smaller. Behind these very promising features of probabilistic decision graphs lies the fact that they integrate into a single coherent framework a number of representational and algorithmic optimizations developed for Bayesian networks (use of hidden variables, context-specific independence, structured representation of conditional probability tables).}, } @PHDTHESIS{JaegerThesis, AUTHOR = {Jaeger, Manfred}, TITLE = {Default Reasoning about Probabilities}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {November}, YEAR = {1995}, ABSTRACT = {Default reasoning about probabilities is the assignment of subjective probabilities on the basis of partial information about an uncertain event, and statistical knowledge about the domain of discourse. In this thesis a logic is developed for representing probabilistic information about both statistical and subjective probabilities. The question is explored about how exactly statistical knowledge should influence the formation of degrees of belief. Strong arguments are presented that justify Cross-Entropy minimization as the appropriate rule of inference. The minimum cross-entropy principle is implemented in a preferred model semantics for the representation language. When probabilities are allowed to take values in real closed fields with a logarithmic function a complete proof system for the resulting logic is obtained.}, } @PROCEEDINGS{JensenPodelski2004, EDITOR = {Jensen, Kurt and Podelski, Andreas}, TITLE = {Tools and algorithms for the construction and analysis of systems : 10th International Conference, TACAS 2004 ; held as part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2004}, PADDRESS = {Berlin}, ADDRESS = {Barcelona, Spain}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2988}, ISBN = {3-540-21299}, YEAR = {2004}, PAGES = {XIV, 608}, } @INPROCEEDINGS{JMW96, AUTHOR = {Jaeger, Manfred and Mannila, Heikki and Weydert, Emil}, EDITOR = {Ng, Raymond}, TITLE = {Data Mining as Selective Theory Extraction in Probabilistic Logic}, BOOKTITLE = {Proceedings of the 1996 SIGMOD Workshop on Research Issues in Data Mining and Knowledge Discovery}, PADDRESS = {Montreal, Canada}, ADDRESS = {Montreal, Canada}, PUBLISHER = {Department of Computer Science, University of British Columbia}, MONTH = {May}, SERIES = {Technical Report 96-08}, YEAR = {1996}, } @INPROCEEDINGS{JohannSocher-Ambrosius93, AUTHOR = {Johann, Patricia and Socher-Ambrosius, Rolf}, EDITOR = {Jouannaud, Jean-Pierre}, TITLE = {Solving Simplificating Ordering Constraints}, BOOKTITLE = {Proceedings of the 1st International Conference on Constraints in Computational Logics (CCL'94)}, INSTITUTION = {Max-Planck-Institut f{\"u}r Informatik}, TYPE = {Technical Report}, PADDRESS = {Berlin, Germany}, ADDRESS = {Munich, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {845}, YEAR = {1994}, PAGES = {352--367}, } @MASTERSTHESIS{JungDiplom2000, AUTHOR = {Jung, Georg}, TITLE = {{Ein Frontend f{\"u}r die Anwendung von Model Checking auf die Analyse von Array Bounds f{\"u}r C Programme}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {May}, YEAR = {2001}, } @PHDTHESIS{KasperDiss1998, AUTHOR = {Kasper, Thomas}, TITLE = {A Unifying Logical Framework for Integer Linear Programming and Finite Domain Constraint Programming}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {December}, YEAR = {1998}, } @INPROCEEDINGS{Kazakov03SubsumptionFLzero, AUTHOR = {Kazakov, Yevgeny and de Nivelle, Hans}, EDITOR = {Calvanese, Diego and De Giacomo, Giuseppe and Franconi, Enrico}, TITLE = {Subsumption of Concepts in ${FL_0}$ for (Cyclic) Terminologies with Respect to Descriptive Semantics is {PSPACE-complete}}, BOOKTITLE = {2003 International Workshop on Description Logics (DL-03)}, ORGANIZATION = {University of Rome "La Sapienza" and Free University of Bolzano/Bozen}, PADDRESS = {Aachen, Germany}, ADDRESS = {Rome, Italy}, PUBLISHER = {CEUR}, MONTH = {September}, SERIES = {CEUR Workshop Proceedings}, VOLUME = {81}, ISBN = {1613-0073}, YEAR = {2003}, PAGES = {56--64}, ABSTRACT = {We close the gap in the complexity classification of subsumption in the simple description logic ${\cal FL}_0$, which allows for conjunctions and universal value restriction only. We prove that the subsumption problem in ${\cal FL}_0$ is PSPACE-complete for descriptive semantics when cyclic definitions are allowed. Our proof uses automata theory and as a by-product we establish the PSPACE-completeness of a certain decision problem for regular languages.}, } @INPROCEEDINGS{Kazakov04GF2N, AUTHOR = {Kazakov, Yevgeny}, EDITOR = {Alferes, Jos{\'e} J{\'u}lio and Leite, João}, TITLE = {A Polynomial Translation from the Two-Variable Guarded Fragment with Number Restrictions to the Guarded Fragment}, BOOKTITLE = {Logics in artificial intelligence : 9th European Conference, JELIA 2004}, PADDRESS = {Berlin, Germany}, ADDRESS = {Lisbon, Portugal}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {3229}, ISBN = {3-540-23242-7}, YEAR = {2004}, PAGES = {372--384}, ABSTRACT = {We consider a two-variable guarded fragment with number restrictions for binary relations and give a satisfiability preserving transformation of formulas in this fragment to the three-variable guarded fragment. The translation can be computed in polynomial time and produces a formula that is linear in the size of the initial formula even for the binary coding of number restrictions. This allows one to reduce reasoning problems for many description logics to the satisfiability problem for the guarded fragment.}, } @INPROCEEDINGS{Kazakov2002, AUTHOR = {Kazakov, Yevgeny}, EDITOR = {Charatonik, Witold and Ganzinger, Harald}, TITLE = {Recursive resolution for modal logic}, BOOKTITLE = {Symposium on the Effectiveness of Logic in Computer Science in Honour of Moshe Vardi}, ORGANIZATION = {International Max Planck Research School for Computer Science (IMPRS)}, TYPE = {Poster}, PADDRESS = {Saarbr{\"u}cken, Germany}, ADDRESS = {Saarbr{\"u}cken, Germany}, PUBLISHER = {Max-Planck-Institut f{\"u}r Informatik}, MONTH = {March}, SERIES = {MPI Research Report}, VOLUME = {MPI-I-2002-2-007}, YEAR = {2002}, PAGES = {11--15}, ABSTRACT = {Resolution for the first order logic can be considered as a practical tool for obtaining a decision procedures for some theories (cf. \cite{arm}). For modal logics, however, there is no uniform formulation of the resolution principle, yet the normal modal logics are the most probable candidates to be decidable theories. The translational methods for modal logic, treated for instance in \cite{ohl}, yet possess some uniformness property, but does not let one to extract proofs from the refutations. On the other hand, direct methods (cf. \cite{far}, \cite{abadi}) are local which gives not much practical use of them. This paper presents some arguments on generalization of the classical propositional resolution method to the language of modal logic. We give a resolution calculus for modal logic $\K$ that inherits some features of classical resolution and propose some suggestions of how can it be used for other modal logics.}, } @PHDTHESIS{Kazakov2005, AUTHOR = {Kazakov, Yevgeny}, TITLE = {Saturation-Based Decision Procedures For Extensions Of The Guarded Fragment}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {March}, YEAR = {2006}, NOTE = {Magna Cum Laude}, ABSTRACT = {We apply the framework of Bachmair and Ganzinger for saturation-based theorem proving to derive a range of decision procedures for logical formalisms, starting with a simple terminological language EL, which allows for conjunction and existential restrictions only, and ending with extensions of the guarded fragment with equality, constants, functionality, number restrictions and compositional axioms of form S ◦ T {\'I} H. Our procedures are derived in a uniform way using standard saturation-based calculi enhanced with simplication rules based on the general notion of redundancy. We argue that such decision procedures can be applied for reasoning in expressive description logics, where they have certain advantages over traditionally used tableau procedures, such as optimal worst-case complexity and direct correctness proofs.}, } @INPROCEEDINGS{KazNiv04ResGFTG, AUTHOR = {Kazakov, Yevgeny and de Nivelle, Hans}, EDITOR = {Basin, David and Rusinowitch, Michael}, TITLE = {A Resolution Decision Procedure for the Guarded Fragment with Transitive Guards}, BOOKTITLE = {Automated reasoning : Second International Joint Conference, IJCAR 2004}, PADDRESS = {Berlin, Germany}, ADDRESS = {Cork, County Cork, Ireland}, PUBLISHER = {Springer}, MONTH = {June}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {3097}, ISBN = {3-540-22345-2}, YEAR = {2004}, PAGES = {122--136}, ABSTRACT = {We show how well-known refinements of ordered resolution, in particular redundancy elimination and ordering constraints in combination with a selection function, can be used to obtain a decision procedure for the guarded fragment with transitive guards. Another contribution of the paper is a special scheme notation, that allows to describe saturation strategies and show their correctness in a concise form.}, } @MASTERSTHESIS{Klotzki-Mastersthesis95, AUTHOR = {Klotzki, Pia}, TITLE = {Wiedemann-Algorithmus zur L{\"o}sung d{\"u}nnbesetzter Gleichungssysteme {\"u}ber Fp}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1995}, } @PHDTHESIS{KorovinPhD2003, AUTHOR = {Korovin, Konstantin}, TITLE = {{Knuth-Bendix} orders in automated deduction and term rewriting}, SCHOOL = {University of Manchester}, TYPE = {Doctoral dissertation}, MONTH = {November}, YEAR = {2003}, ABSTRACT = {Ordering restrictions play a crucial role in automated deduction. In particular, orders are used extensively for pruning search space in automated theorem provers and for rewriting-based reasoning and computation. There are two classes of orders that are widely used in automated deduction: Knuth-Bendix orders and various versions of recursive path orders. Despite the fact that Knuth-Bendix orders were discovered earlier than recursive path orders, and since then have been used in many state-of-the-art automated theorem provers; the decidability and complexity of many important problems related to these orders remained open. In this thesis we try to close this gap and provide various decidability and complexity results for a number of important decision problems related to Knuth-Bendix orders. We prove the decidability and NP-completeness of the problem of solving Knuth-Bendix ordering constraints. In the case of constraints consisting of single inequalities we present a polynomial-time algorithm. We also prove the decidability of the problem of solving general first-order Knuth-Bendix ordering constraints over unary signatures. Another problem we study is the orientability problem by Knuth-Bendix orders. We present a polynomial-time algorithm for orientability of systems consisting of term rewrite rules and equalities by Knuth-Bendix orders, and prove that this problem is P-complete. Finally, we show that it is possible to extend Knuth-Bendix orders to AC-compatible orders preserving attractive properties of Knuth-Bendix orders. }, } @INPROCEEDINGS{KorovinVoronkov:CADE03:ACKBO, AUTHOR = {Korovin, Konstantin and Voronkov, Andrei}, EDITOR = {Baader, Franz}, TITLE = {{AC-compatible} {Knuth-Bendix} Order}, BOOKTITLE = {Automated deduction, CADE-19 : 19th International Conference on Automated Deduction}, PADDRESS = {Berlin, Germany}, ADDRESS = {Miami, Florida}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2741}, YEAR = {2003}, PAGES = {47--59}, ABSTRACT = {We introduce a family of AC-compatible Knuth-Bendix simplification orderings which are AC-total on ground terms. Our orderings preserve attractive features of the original Knuth-Bendix orderings such as polynomial algorithm for comparing terms; the orderings admit computationally efficient approximations like checking weights of terms; and prefer light terms to heavy ones. This makes them especially suited for automated deduction where efficient treatment of orderings is desirable.}, } @ARTICLE{KorovinVoronkov:IC:2003, AUTHOR = {Korovin, Konstantin and Voronkov, Andrei}, JOURNAL = {Information and Computation}, TITLE = {Orienting rewrite rules with the {Knuth-Bendix} order}, ADDRESS = {Amsterdam, The Netherlands}, NUMBER = {2}, PUBLISHER = {Elsevier}, VOLUME = {183}, YEAR = {2003}, PAGES = {165--186}, ABSTRACT = {We consider two decision problems related to the Knuth-Bendix order (KBO). The first problem is \emph{orientability}: given a system of rewrite rules $R$, does there exist an instance of KBO which orients every ground instance of every rewrite rule in $R$. The second problem is whether a given instance of KBO orients every ground instance of a given rewrite rule. This problem can also be reformulated as the problem of solving a single ordering constraint for the KBO. We prove that both problems can be solved in the time polynomial in the size of the input. The polynomial-time algorithm for orientability builds upon an algorithm for solving systems of homogeneous linear inequalities over integers. We show that the orientability problem is P-complete. The polynomial-time algorithm for solving a single ordering constraint does not need to solve systems of linear inequalities and can be run in time $O(n^2)$. Also we show that if a system is orientable using a real-valued instance of KBO, then it is also orientable using an integer-valued instance of KBO. Therefore, all our results hold both for the integer-valued and the real-valued KBO.}, } @INPROCEEDINGS{KorovinVoronkov:LICS03:EqOrientability, AUTHOR = {Korovin, Konstantin and Voronkov, Andrei}, EDITOR = {Kolaitis, Phokion}, TITLE = {Orienting Equalities with the {Knuth-Bendix} Order}, BOOKTITLE = {18th Annual IEEE Symposium on Logic in Computer Science (LICS-03)}, ORGANIZATION = {Institute of Electrical and Electronics Engineers (IEEE)}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Ottawa, Canada}, PUBLISHER = {IEEE}, YEAR = {2003}, PAGES = {75--84}, ABSTRACT = {Orientability of systems of equalities is the following problem: given a system of equalities $s_1 \eql t_1, \ldots, s_n \eql t_n$, does there exist a simplification ordering $\succ$ which orients the system, that is for every $i \in \{1,...,n\}$, either $s_i \succ t_i$ or $t_i \succ s_i$. This problem can be used in rewriting for finding a canonical rewrite system for a system of equalities and in theorem proving for adjusting simplification orderings during completion. We prove that (rather surprisingly) the problem can be solved in polynomial time when we restrict ourselves to the Knuth-Bendix orderings.}, } @ARTICLE{KorovinVoronkov:TOCL:2004, AUTHOR = {Korovin, Konstantin and Voronkov, Andrei}, JOURNAL = {ACM Transactions on Computational Logic}, TITLE = {{Knuth-Bendix} constraint solving is {NP-complete}}, NUMBER = {2}, PUBLISHER = {ACM}, VOLUME = {6}, YEAR = {2005}, PAGES = {361--388}, ABSTRACT = {We show the NP-completeness of the existential theory of term algebras with the Knuth--Bendix order by giving a nondeterministic polynomial-time algorithm for solving Knuth--Bendix ordering constraints.}, } @INPROCEEDINGS{KraanBasinBundy93a, AUTHOR = {Kraan, Ina and Basin, David A. and Bundy, Alan}, EDITOR = {Lau, K. K. and Clement, T.}, TITLE = {Logic Program Synthesis via Proof Planning}, BOOKTITLE = {International Workshop on Logic Program Synthesis and Transformation (LOPSTR '92)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Manchester, UK}, PUBLISHER = {Springer}, MONTH = {June}, YEAR = {1993}, PAGES = {1--14}, NOTE = {Also available as Research Report MPI-I-92-244}, ABSTRACT = {We propose a novel approach to automating the synthesis of logic programs: Logic programs are synthesized as a by-product of the planning of a verification proof. The approach is a two-level one: At the object level, we prove program verification conjectures in a sorted, first-order theory. The conjectures are of the form $\forall \overrightarrow{args.} prog(\overrightarrow {args}) \leftrightarrow spec(\overrightarrow{args})$. At the meta-level, we plan the object-level verification with an unspecified program definition. The definition is represented with a (second-order) meta-level variable, which becomes instantiated in the course of the planning. This technique is an application of the Clam proof planning system. Clam is currently powerful enough to plan verification proofs for given programs. We show that, if Clam's use of middle-out reasoning is extended, it will also be able to synthesize programs.}, } @INPROCEEDINGS{KraanBasinBundy93b, AUTHOR = {Kraan, Ina and Basin, David A. and Bundy, Alan}, TITLE = {Middle-Out Reasoning for Logic Program Synthesis}, BOOKTITLE = {Proc.~10th Intern. Conference on Logic Programing (ICLP '93)}, PADDRESS = {Cambridge, USA}, ADDRESS = {Budapest, Hungary}, PUBLISHER = {MIT Press}, YEAR = {1993}, PAGES = {441--455}, NOTE = {Also available as Research Report MPI-I-93-214}, ABSTRACT = {Logic programs can be synthesized as a by-product of the planning of their verification proofs. This is achieved by using higher-order variables at the proof planning level, which become instantiated in the course of planning. We illustrate two uses of such variables in proof planning for program synthesis, one for synthesis proper and one for the selection of induction schemes. We demonstrate that the use of these variables can be restricted naturally in such a way that terms containing them form a tractable extension of first-order terms.}, } @ARTICLE{KraanBasinBundy96, AUTHOR = {Kraan, Ina and Basin, David A. and Bundy, Alan}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {Middle-out reasoning for synthesis and induction}, NUMBER = {1/2}, PUBLISHER = {Kluwer}, MONTH = {March}, VOLUME = {16}, ISBN = {0168-7433}, YEAR = {1996}, PAGES = {113--145}, ABSTRACT = {We develop two applications of middle-out reasoning in inductive proofs: the logic program synthesis and the selection of induction schemes. Middle-out reasoning uses variables to represent unknown terms and formulae. Unification instantiates the variables in the subsequent planning, while proof planning provides the necessary search control. Middle-out reasoning is used for synthesis by planning the verification of an unknown logic program: the program body is represented with a meta-variable. The planning results both in an instantiation of the program body and a plan for the verification of that program. If the plan executes successfully, the synthesized program is partially correct and complete. Middle-out reasoning is also used to select induction schemes. In middle-out induction, we set up a schematic step case by representing the constructors that are applied to induction variables with meta-variables. Once the step case is complete, the instantiated variables correspond to an induction appropriate to the recursion of the program. We have implemented these techniques as an extension of the proof planning system CLAM, called Periwinkle, and synthesized a variety of programs fully automatically.}, } @INPROCEEDINGS{KrischerBockmayr91a, AUTHOR = {Krischer, Stefan and Bockmayr, Alexander}, EDITOR = {Book, R.}, TITLE = {Detecting Redundant Narrowing Derivations by the {LSE-SL} Reducibility Test}, BOOKTITLE = {Proceedings of the 4th International Conference on Rewriting Techniques and Applications (RTA '91)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Como, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {488}, YEAR = {1991}, PAGES = {74--85}, ABSTRACT = {Rewriting and narrowing provide a nice theoretical framework for the integration of logic and functional programming. For practical applications however, narrowing is still much too inefficient. In this paper we show how reducibility tests can be used to detect redundant narrowing derivations. We introduce a new narrowing strategy, LSE-SL left-to-right basic normal narrowing, prove its completeness for arbitrary canonical term rewriting systems, and demonstrate how it increases the efficiency of the narrowing process.}, } @INPROCEEDINGS{KrishnaRao95, AUTHOR = {Krishna Rao, M. R. K.}, EDITOR = {Wiedermann, Jir{\'i} and H{\'a}jek, Petr}, TITLE = {Graph reducibility of term rewriting systems}, BOOKTITLE = {Proceedings of Mathematical Foundations of Computer Science}, PADDRESS = {Berlin, Germany}, ADDRESS = {Prague, Czech Republic}, PUBLISHER = {Springer}, MONTH = {August}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {969}, ISBN = {3-540-60246-1}, YEAR = {1995}, PAGES = {371--381}, ABSTRACT = {Term rewriting is generally implemented using graph rewriting for efficiency reasons. Graph rewriting allows sharing of common structures thereby saving both time and space. This implementation is sound in the sense that computation of a normal form of a graph yields a normal form of the corresponding term. However, certain properties of term rewriting systems are not reflected in their graph rewriting implementations. Weak normalization is one such property. An undesirable side effect of this is that it may be impossible to compute a normal form of a normalizable term. In this paper, we present some sufficient conditions for preservation of weak normalization and discuss the implication of the results to modularity.}, } @INPROCEEDINGS{KrishnaRao96a, AUTHOR = {Krishna Rao, M. R. K.}, EDITOR = {Arikawa, Setsuo and Sharma, Arun}, TITLE = {A class of Prolog programs inferable from positive data}, BOOKTITLE = {Algorithmic Learning Theory}, PADDRESS = {Berlin, Germany}, ADDRESS = {Sydney, Australia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1160}, ISBN = {3-540-61863-5}, YEAR = {1996}, PAGES = {272--284}, ABSTRACT = {In this paper, we identify a class of Prolog programs inferable from positive data. Our approach is based on moding information and linear predicate inequalities between input terms and output terms. Our results generalize the results of Arimura and Shinohara (1994). Standard programs for {\tt reverse, quick-sort, merge-sort} are a few examples of programs that can be handled by our results but not by the earlier results of Arimura and Shinohara (1994). The generality of our results follows from the fact that we treat logical variables as transmitters for broadcasting communication, whereas Arimura and Shinohara (1994) treat them as point-to-point communication channels.}, } @INPROCEEDINGS{KrishnaRao96b, AUTHOR = {Krishna Rao, M. R. K.}, EDITOR = {Maher, Michael}, TITLE = {Completeness results for basic narrowing in non-copying implementations}, BOOKTITLE = {Logic Programming}, ORGANIZATION = {The Association for Logic Programming}, PADDRESS = {Cambridge, USA}, ADDRESS = {Bonn, Germany}, PUBLISHER = {MIT Press}, SERIES = {JICSLP}, ISBN = {0-262-63173-3}, YEAR = {1996}, PAGES = {393--407}, ABSTRACT = {Narrowing and rewriting play an important role in giving the operational semantics of languages that integrate functional and logic programming. These two operations are usually implemented using tree representation of terms and atoms. Such implementations do not allow sharing of similar structures. In contrast to this, implementations which use (directed acyclic) graph representations of terms and atoms allow sharing of similar structures. Such sharing saves space and avoids repetition of computations. Term graph rewriting is one of the nice models proposed in the literature to facilitate sharing of similar structures. In this paper, we study completeness of basic narrowing in term graph rewriting. Our results show that term graph rewriting not only improves efficiency but even facilitates more general results on the completeness of basic narrowing than the results known in term rewriting (which use tree representations)}, } @INPROCEEDINGS{KrishnaRao96c, AUTHOR = {Krishna Rao, M. R. K.}, EDITOR = {Anjaneyulu, KSR and Sasikumar, M. and Ramani, S.}, TITLE = {Learning Prolog programs from examples}, BOOKTITLE = {Knowledge Based Computer Systems}, PADDRESS = {New Delhi, India}, ADDRESS = {Bombay, India}, PUBLISHER = {Narosa}, ISBN = {81-7319-149-2}, YEAR = {1996}, PAGES = {19--30}, ABSTRACT = {Logic programs with elegant and simple declarative semantics have become very common in many areas of artificial intelligence such as knowledge acquisition, knowledge representation and common sense and legal reasoning. For example, in Human GENOME project, logic programs are used in the analysis of amino acid sequences, protein structure and drug design etc. In this paper, we investigate the problem of learning logic (Prolog) programs from examples and present an inference algorithm for a class of programs. This class of programs (called one-recursive programs) is based on the divide-and-conquer approach and mode/type annotations. Our class is very rich and includes many programs from Sterling and Shapiro's book including {\tt append, merge, split, insert, insertion-sort, preorder} and {\tt inorder} traversal of binary trees, polynomial recognition, derivatives, sum of a list of natural numbers etc., whereas earlier results can only deal with very simple programs without local variables and at most two clauses and one predicate \cite{colt92}. Further, our algorithm does not need examples for auxiliary predicates, but only for the target predicate.}, } @INPROCEEDINGS{KrishnaRao96d, AUTHOR = {Krishna Rao, M. R. K.}, EDITOR = {Ganzinger, Harald}, TITLE = {Modularity of termination in term graph rewriting}, BOOKTITLE = {Rewriting Techniques and Applications}, PADDRESS = {Berlin, Germany}, ADDRESS = {New Brunswick}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1103}, ISBN = {3-540-61464-8}, YEAR = {1996}, PAGES = {230--244}, ABSTRACT = {Term rewriting is generally implemented using graph rewriting for efficiency reasons. Graph rewriting allows sharing of common structures thereby saving both time and space. This implementation is sound in the sense that computation of a normal form of a graph yields a normal form of the corresponding term. In this paper, we study modularity of termination of the graph reduction. Unlike in the case of term rewriting, termination is modular in graph rewriting for a large class of systems. Our results generalize the results of Plump (1992) and Kurihara and Ohuchi (1995).}, } @INPROCEEDINGS{KrishnaRao96e, AUTHOR = {Krishna Rao, M. R. K.}, EDITOR = {Wirsing, Martin and Nivat, Maurice}, TITLE = {Some characteristics of strong innermost normalization}, BOOKTITLE = {Algebraic Methodology and Software Technology, 5th International Conference, AMAST '96}, PADDRESS = {Berlin, Germany}, ADDRESS = {Munich, Germany}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1101}, ISBN = {3-540-61463-X}, YEAR = {1996}, PAGES = {406--420}, ABSTRACT = {A term rewriting system is {\em strongly innermost normalizing } if every innermost derivation of it is of finite length. This property is very important in the integration of functional and logic programming paradigms. Unlike termination, strong innermost normalization is not preserved under subsystems, i.e., every subsystem of a strongly innermost normalizing need not be strongly innermost normalizing. Preservation of a property under subsystems is important in analyzing systems in a modular fashion. In this paper, we identify a few classes of {\trs}s which enjoy this property. These classes are of particular interest in studying modularity of composable and hierarchical combinations. It is also proved that the choice of the innermost redex to be reduced at any step has no bearing on termination (finiteness) of innermost derivations. It may be noted that such selection invariance does not hold for outermost derivations. The proof techniques used are novel and involve oracle based reasoning --which is very sparsely used in the rewriting literature.}, } @ARTICLE{KrishnaRao97a, AUTHOR = {Krishna Rao, M. R. K.}, JOURNAL = {Theoretical Computer Science}, TITLE = {A framework for incremental learning of logic programs}, ADDRESS = {Amsterdam, the Netherlands}, PUBLISHER = {Elsevier}, VOLUME = {185}, YEAR = {1997}, PAGES = {191--213}, } @ARTICLE{KrishnaRao98a, AUTHOR = {Krishna Rao, M. R. K.}, JOURNAL = {Theoretical Computer Science}, TITLE = {Modular Aspects of term graph rewriting}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {1/2}, PUBLISHER = {Elsevier}, MONTH = {November}, VOLUME = {208}, ISBN = {0304-3975}, YEAR = {1998}, PAGES = {59--86}, NOTE = {-}, ABSTRACT = {-}, } @ARTICLE{KrishnaRaoActaInformatica, AUTHOR = {Krishna Rao, M. R. K.}, JOURNAL = {Acta Informatica}, TITLE = {Relating confluence, innermost-confluence and outermost-confluence properties of term rewriting systems}, ADDRESS = {Berlin, Germany}, NUMBER = {6}, PUBLISHER = {Springer}, MONTH = {September}, VOLUME = {33}, ISBN = {0001-5903}, YEAR = {1996}, PAGES = {595--606}, ABSTRACT = {Innermost-confluence is important in giving call-by-value and denotational semantics and outermost-confluence is important in giving call-by-need and lazy semantics of programs. In this paper, we give a few sets of sufficient conditions under which the properties of confluence, innermost-confluence and outermost-confluence coincide. Confluence and innermost-confluence coincide for weakly innermost normalizing overlay systems and confluence and outermost-confluence coincide for outermost normalizing left-linear overlay systems. In general, every weakly innermost (outermost) normalizing {\em confluent} system is {\em innermost (outermost) confluent} but the converse is not true.}, } @INPROCEEDINGS{KrishnaRaoALT, AUTHOR = {Krishna Rao, M. R. K.}, EDITOR = {Jantke, Klaus and Shinohara, Takeshi and Zeugmann, Thomas}, TITLE = {Incremental Learning of Logic Programs}, BOOKTITLE = {Proceedings of International Workshop on Algorithmic Learning Theory}, PADDRESS = {Berlin, Germany}, ADDRESS = {Fukuoka, Japan}, PUBLISHER = {Springer}, MONTH = {October}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {997}, ISBN = {3-540-60454-5}, YEAR = {1995}, PAGES = {95--109}, ABSTRACT = {In this paper, we identify a class of polynomial-time learnable logic programs. These programs can be learned from examples in an incremental fashion using the already defined predicates as background knowledge. Our class properly contains the class of innermost simple programs of Yamamoto (1993) and the class of hereditary programs of Miyano, Shinohara and Shinohara (1991). Standard programs for {\tt multiplication, quick-sort, reverse} and $\tt merge$ are a few examples of programs that can be handled by our results but not by the earlier results.}, } @INPROCEEDINGS{KrishnaRaoSAS, AUTHOR = {Krishna Rao, M. R. K. and Shyamasundar, R. K.}, EDITOR = {Mycroft, Alan}, TITLE = {Unification-free Execution of Well-moded Prolog Programs}, BOOKTITLE = {Proc. of International Static Analysis Symposium}, PADDRESS = {Berlin, Germany}, ADDRESS = {Glasgow, Scotland}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {983}, ISBN = {3-540-60360-3}, YEAR = {1995}, PAGES = {243--260}, } @INPROCEEDINGS{KrishnaRaoTAPSOFT, AUTHOR = {Krishna Rao, M. R. K.}, EDITOR = {Mosses, Peter and Nielsen, Mogens and Schwartzbach, Michael}, TITLE = {Semi-completeness of Hierarchical and Super-hierarchical Combinations of Term Rewriting Systems}, BOOKTITLE = {Proceedings of the 6th Joint Conference on Theory and Practice of Software Development}, PADDRESS = {Berlin, Germany}, ADDRESS = {{\AA}rhus, Denmark}, PUBLISHER = {Springer}, MONTH = {May}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {915}, ISBN = {3-540-59293-8}, YEAR = {1995}, PAGES = {379--393}, ABSTRACT = {In this paper, we study modular aspects of hierarchical and super hierarchical combinations of term rewriting systems. In particular, a sufficient condition for modularity of semi-completeness of hierarchical and super hierarchical combinations is proposed. We first establish modularity of weak normalization for this class (defined by the sufficient condition) and modularity of semi-completeness for a class of crosswise independent unions. From these results, we obtain modularity of semi-completeness for a class of hierarchical and super hierarchical combinations. Our results generalize the main result of Ohlebusch (1994). The notion of crosswise independent unions is a generalization of both constructor sharing unions as well as Plump's crosswise disjoint unions.}, } @ARTICLE{KrishnaRaoTCS, AUTHOR = {Krishna Rao, M. R. K.}, JOURNAL = {Theoretical Computer Science}, TITLE = {Modular Proofs for Completeness of hierarchical term rewriting systems}, NUMBER = {2}, PUBLISHER = {North-Holland Publishing Co.}, MONTH = {December}, VOLUME = {151}, ISBN = {0304-3975}, YEAR = {1995}, PAGES = {487--512}, ABSTRACT = {In this paper, we study modular aspects of hierarchical combinations of term rewriting systems. System $\R_0 \cup \R_1$ is a hierarchical combination if the defined symbols of two subsystems, $\R_0$ and $\R_1$ are disjoint, some of the defined symbols of $\R_0$ are constructors in $\R_1$ and the defined symbols of $\R_1$ do not occur in $\R_0$. It is shown that in hierarchical combinations, a reduction can increase the rank of a term. Therefore, techniques employed in proving modularity results for direct sums and constructor sharing systems are not applicable for hierarchical combinations. We propose a set of sufficient conditions for modularity of completeness of hierarchical combinations. The sufficient conditions are syntactic ones (about recursion) based on constructor discipline. We prove our result by showing that hierarchical combination $\R_0 \cup \R_1$ satisfying our sufficient conditions is innermost normalizing and locally confluent, if $\R_0$ and $\R_1$ are complete constructor systems. The result generalizes Middeldorp and Toyama's result on modularity of completeness for shared constructor systems.}, } @INPROCEEDINGS{KupferschmidEtAl2006, AUTHOR = {Kupferschmid, Sebastian and Hoffmann, J{\"o}rg and Dierks, Henning and Behrmann, Gerd}, EDITOR = {Valmari, Antti}, TITLE = {Adapting an AI Planning Heuristic for Directed Model Checking}, BOOKTITLE = {Model checking software : 13th International SPIN Workshop}, PADDRESS = {Berlin, Germany}, ADDRESS = {Vienna, Austria}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3925}, ISBN = {978-3-540-33102-5}, YEAR = {2006}, PAGES = {35--52}, ABSTRACT = {There is a growing body of work on directed model checking, which improves the falsification of safety properties by providing heuristic functions that can guide the search quickly towards short error paths. Techniques of this kind have also been made very successful in the area of AI Planning. Our main technical contribution is the adaptation of the most successful heuristic function from AI Planning to the model checking context, yielding a new heuristic for directed model checking. The heuristic is based on solving an abstracted problem in every search state. We adapt the abstraction and its solution to networks of communicating automata annotated with (constraints and effects on) integer variables. Since our ultimate goal in this research is to also take into account clock variables, as used in timed automata, our techniques are implemented inside UPPAAL. We run experiments in some toy benchmarks for timed automata, and in two timed automata case studies originating from an industrial project. Compared to both blind search and some previously proposed heuristic functions, we consistently obtain significant, sometimes dramatic, search space reductions, resulting in likewise strong reductions of runtime and memory requirements. This work was partly supported by the German Research Council (DFG) as part of the Transregional Collaborative Research Center “Automatic Verification and Analysis of Complex Systems” (SFB/TR 14 AVACS). See http://www.avacs.org/ for more information.}, } @UNPUBLISHED{Lee2004, AUTHOR = {Lee, Chin Soon}, TITLE = {Size-change Termination Analyzer}, YEAR = {2004}, NOTE = {A tool for program analysis available on the internet at \verb+http://www.mpi-sb.mpg.de/~soonlee/sct.html+}, } @ARTICLE{Lee2009, AUTHOR = {Lee, Chin Soon}, JOURNAL = {ACM Transactions on Programming Languages and Systems}, TITLE = {Ranking functions for size-change termination}, ADDRESS = {New York, NY}, NUMBER = {3}, PUBLISHER = {ACM}, VOLUME = {31}, ISBN = {0164-0925}, DOI = {10.1145/1498926.1498928}, YEAR = {2009}, PAGES = {10:1--10:42}, } @ARTICLE{lepl:94a, AUTHOR = {Lee, Shie-Jue and Plaisted, David A.}, JOURNAL = {Artificial Intelligence}, TITLE = {Problem solving by searching for models with a theorem prover}, NUMBER = {1/2}, PUBLISHER = {North-Holland Publishing Co.}, VOLUME = {69}, ISBN = {0004-3702}, YEAR = {1994}, PAGES = {205--233}, } @ARTICLE{lepl:94b, AUTHOR = {Lee, Shie-Jue and Plaisted, David A.}, JOURNAL = {Methods of Logic in Computer Science}, TITLE = {Use of replace rules in theorem proving}, VOLUME = {1}, YEAR = {1994}, PAGES = {217--240}, } @INPROCEEDINGS{LETZ03, AUTHOR = {Letz, Reinhold and Stenz, Gernot}, EDITOR = {Cialdea Mayer, Marta and Pirri, Fiora}, TITLE = {Universal variables in disconnection tableaux}, BOOKTITLE = {Automated reasoning with analytical tableaux and related methods : International Conference, TABLEAUX 2003}, PADDRESS = {Berlin, Germany}, ADDRESS = {Rome, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2796}, ISBN = {3-540-40787-1}, YEAR = {2003}, PAGES = {117--133}, } @ARTICLE{LetzWeidenbach98, AUTHOR = {Letz, Reinhold and Weidenbach, Christoph}, JOURNAL = {KI, Organ des Fachbereichs 1 "K{\"u}nstliche Intelligenz'' der Gesellschaft f{\"u}r Informatik e.V.}, TITLE = {{Paradigmen und Perspektiven der automatischen Deduktion}}, VOLUME = {4}, YEAR = {1998}, PAGES = {15--19}, } @ARTICLE{LeuschelPodelski2004, AUTHOR = {Podelski, Andreas}, JOURNAL = {Theory and Practice of Logic Programming (TPLP)}, TITLE = {Introduction to the Special Issue on Verification and Computational Logic}, ADDRESS = {Cambridge, UK}, NUMBER = {5-6}, PUBLISHER = {Cambridge University Press}, VOLUME = {4}, ISBN = {1471-0684}, YEAR = {2004}, PAGES = {541--751}, } @MASTERSTHESIS{Leven-Diplom98, AUTHOR = {Leven, Peter}, TITLE = {Integrating Clausal Decision Procedures in a Tactic Based Theorem Prover}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1998}, } @ARTICLE{LevyVeanes99, AUTHOR = {Levy, Jordi and Veanes, Margus}, JOURNAL = {Information and Computation}, TITLE = {On the Undecidability of Second-Order Unification}, ADDRESS = {London, UK}, PUBLISHER = {Academic Press}, VOLUME = {159}, ISBN = {0890-5401}, YEAR = {2000}, PAGES = {125--150}, ABSTRACT = {There is a close relationship between word unification and second-order unification. This similarity has been exploited, for instance, for proving decidability of monadic second-order unification, and decidability of linear second-order unification when no second-order variable occurs more than twice. The attempt to prove the second result for (non-linear) second-order unification failed, and lead instead to a natural reduction from simultaneous rigid E-unification to this problem. This reduction is the first main result of this paper, and it is the starting point for proving some novel results about the undecidability of second-order unification presented in the rest of the paper. We prove that second-order unification is \emph{undecidable} in the following three cases: 1) each second-order variable occurs at most twice and there are only two second-order variables; 2) there is only one second-order variable and it is unary; 3) the conditions (i--iv) hold for some fixed integer $n$: (i) the arguments of all second-order variables are ground terms of size less than $n$, (ii) the arity of all second-order variables is less than $n$, (iii) the number of occurrences of second-order variables is at most 5, (iv) there is either a single second-order variable, or there are two second-order variables and no first-order variables.}, } @INPROCEEDINGS{LisaCSL, AUTHOR = {Abdelwaheb, Ayari and Basin, David A. and Podelski, Andreas}, EDITOR = {Nielsen, Mogens and Thomas, Wolfgang}, TITLE = {LISA: A Specification Language Based on WS2S}, BOOKTITLE = {Proceedings of the 11th International Workshop on Computer Science Logic (CSL-97)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Aarhus, Denmark}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1414}, ISBN = {3-540-64570-5}, YEAR = {1998}, PAGES = {18--34}, ABSTRACT = {We integrate two concepts from programming languages into a specification language based on WS2S, namely high-level data structures such as records and recursively-defined datatypes (WS2S is the weak second-order monadic logic of two successors). Our integration is based on a new logic whose variables range over record-like trees and an algorithm for translating datatypes into tree automata. We have implemented Lisa, a prototype system based on these ideas, which, when coupled with a decision procedure for WS2S like the Mona system, results in a verification tool that supports both high-level specifications and complexity estimations for the running time of the decision procedure.}, } @ARTICLE{LoechnerHillenbrandAICOM2002, AUTHOR = {L{\"o}chner, Bernd and Hillenbrand, Thomas}, JOURNAL = {AI Communications}, TITLE = {A Phytography of {WALDMEISTER}}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {2-3}, PUBLISHER = {IOS Press}, MONTH = {August}, VOLUME = {15}, ISBN = {0921-7126}, YEAR = {2002}, PAGES = {127--133}, ABSTRACT = {The architecture of the {Waldmeister} prover for unit equational deduction is based on a strict separation of active and passive facts. After an inspection of the system's proof procedure, the representation of each of the central data structures is outlined, namely indexing for the active facts, compression for the passive facts, successor sets for the hypotheses, and minimal recording of inference steps for the proof object. In order to cope with large search spaces, specialized redundancy criteria are employed, and the empirically gained control knowledge is integrated to ease the use of the system. The paper concludes with a quantitative comparison of the {Waldmeister} versions over the years, and a view of the future prospects.}, } @ARTICLE{LuWu1999, AUTHOR = {Lu, Mi and Wu, Jinzhao}, JOURNAL = {Journal of Applied Non-Classical Logics}, TITLE = {On Theorem proving in Annotated Logics}, ADDRESS = {Paris, France}, NUMBER = {2}, PUBLISHER = {Hermes}, MONTH = {June}, VOLUME = {10}, ISBN = {1166-3081}, YEAR = {2000}, PAGES = {121--143}, } @INPROCEEDINGS{Madden-1992, AUTHOR = {Madden, Peter}, EDITOR = {Kapur, Deepak}, TITLE = {Automated Program Transformation Through Proof Transformation}, BOOKTITLE = {Proceedings of the 11th International Conference on Automated Deduction (CADE-11)}, PADDRESS = {Heidelberg, Germany}, ADDRESS = {Saratoga Springs, NY}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {607}, YEAR = {1992}, PAGES = {446--460}, } @INPROCEEDINGS{Madden-93a, AUTHOR = {Madden, Peter and Bundy, Alan}, TITLE = {General Proof Theoretic Techniques for Automatic Programing}, BOOKTITLE = {Proceedings of the EAST-WEST AI CONFERENCE: From Theory to Practice - EWAIC'93}, MONTH = {December}, YEAR = {1993}, } @INPROCEEDINGS{Madden-95a, AUTHOR = {Madden, Peter}, TITLE = {Program improvement by proof planning}, BOOKTITLE = {Proceedings of British Colloquium on Theoretical Computer Science (BCTCS 11)}, ADDRESS = {University of Wales, Swansea, Wales}, YEAR = {1995}, } @ARTICLE{Madden-JAR, AUTHOR = {Madden, Peter and Bundy, Alan and Smaill, Alan}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {Recursive Program Optimization Through Inductive Synthesis Proof Transformation}, NUMBER = {1}, PUBLISHER = {Kluwer}, VOLUME = {22}, ISBN = {0168-7433}, YEAR = {1999}, PAGES = {65--115}, NOTE = {Also available as Research Report MPI-I-94-239, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken}, ABSTRACT = {The research described in this paper involved developing transformation techniques which increase the efficiency of the original program, the *source*, by transforming its synthesis proof into one, the *target*, which yields a computationally more efficient algorithm. We describe a working proof transformation system which, by exploiting the duality between mathematical induction and recursion, employs the novel strategy of optimizing recursive programs by transforming inductive proofs. We compare and contrast this approach with the more traditional approaches to program transformation, and highlight the benefits of proof transformation with regards to search, correctness, automatability and generality.}, } @INPROCEEDINGS{Madden94a-djki, AUTHOR = {Madden, Peter}, EDITOR = {Nebel, Bernhard and Dreschler-Fischer, Leonie}, TITLE = {Formal Methods for Automated Program Improvement}, BOOKTITLE = {KI-94: Advances in Artificial Intelligence. Proceedings of the 18th German Annual Conference on Artificial Intelligence}, PADDRESS = {Berlin, Germany}, ADDRESS = {Saarbr{\"u}cken, Germany}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {861}, YEAR = {1994}, PAGES = {367--378}, NOTE = {Also available as Research Report MPI-I-94-238, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken}, ABSTRACT = {Systems supporting the manipulation of non-trivial program code are complex and are at best semi-automatic. However, formal methods, and in particular theorem proving, are providing a growing foundation of techniques for automatic program development (synthesis, improvement, transformation and verification). In this paper we report on novel research concerning: (1) the exploitation of synthesis proofs for the purposes of automatic program optimization by the transformation of proofs, and; (2) the automatic synthesis of efficient programs from standard equational definitions. A fundamental theme exhibited by our research is that mechanical program construction, whether by direct synthesis or transformation, is tantamount to program verification plus higher-order reasoning. The exploitation of the proofs-as-programs paradigm lends our approach numerous advantages over more traditional approaches to program improvement. For example, we are able to automate the identification of efficient recursive data-types which usually correspond to *eureka* steps in ``pure'' transformational techniques such as unfold/fold. Furthermore, all transformed, and synthesized, programs are guaranteed correct with respect to their specifications.}, } @INPROCEEDINGS{MaddenGreen94b-aismc2, AUTHOR = {Madden, Peter and Green, Ian}, EDITOR = {Calmet, Jacques and Campbell, John A.}, TITLE = {A General Technique for Automatic Optimization by Proof Planning}, BOOKTITLE = {Proceedings of the 2nd International Conference on Artificial Intelligence and Symbolic Mathematical Computing (AISMC-2)}, PADDRESS = {Berlin, Germany}, ADDRESS = {King's College, Cambridge, England}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {958}, YEAR = {1995}, PAGES = {80--96}, NOTE = {Also available as Research Report MPI-I-94-239, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken. Extended version to appear in Journal of Automated Reasoning}, ABSTRACT = {The use of *proof plans* -- formal patterns of reasoning for theorem proving -- to control the (automatic) synthesis of efficient programs from standard definitional equations is described. A general framework for synthesizing efficient programs, using tools such as higher-order unification, has been developed and holds promise for encapsulating an otherwise diverse, and often ad hoc, range of transformation techniques. A prototype system has been implemented. We illustrate the methodology by a novel means of affecting *constraint-based* program optimization through the use of proof plans for mathematical induction. \par Proof plans are used to control the (automatic) synthesis of functional programs, specified in a standard equational form, E, by using the proofs as programs principle. The goal is that the program extracted from a constructive proof of the specification is an optimization of that defined solely by E. Thus the theorem proving process is a form of program optimization allowing for the construction of an efficient, *target*, program from the definition of an inefficient, *source*, program. \par The general technique for controlling the syntheses of efficient programs involves using E to specify the target program and then introducing a new sub-goal into the proof of that specification. Different optimizations are achieved by placing different characterizing restrictions on the form of this new sub-goal and hence on the subsequent proof. Meta-variables and higher-order unification are used in a technique called *middle-out reasoning* to circumvent eureka steps concerning, amongst other things, the identification of recursive data-types, and unknown constraint functions. Such problems typically require user intervention.}, } @INPROCEEDINGS{Maier2001, AUTHOR = {Maier, Patrick}, EDITOR = {Orejas, Fernando and Spirakis, Paul G. and van Leeuwen, Jan}, TITLE = {A Set-Theoretic Framework for Assume-Guarantee Reasoning}, BOOKTITLE = {Proceedings of the 28th International Colloquium on Automata, Languages and Programming (ICALP-2001)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Crete, Greece}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2076}, ISBN = {3-540-42287-0}, YEAR = {2001}, PAGES = {821--834}, ABSTRACT = {We present a circular assume-guarantee rule in an abstract setting (of sets over a partially-ordered domain). The rule has a mathematically concise side condition. Now, in order to prove an assume-guarantee rule in a concrete setting, all we need to do is to is to instantiate the abstract setting and check the side condition; i.e., we need not redo the notorious circularity argument again. We use this framework to prove a new assume-guarantee rule for Kripke structures. That rule generalizes existing assume-guarantee rules for other settings such as Reactive Modules or Mealy machines.}, } @INPROCEEDINGS{Maier2002, AUTHOR = {Maier, Patrick}, EDITOR = {Charatonik, Witold and Ganzinger, Harald}, TITLE = {A Framework for Circular Assume-Guarantee Rules}, BOOKTITLE = {Symposium on the Effectiveness of Logic in Computer Science in Honour of Moshe Vardi}, PADDRESS = {Saarbr{\"u}cken, Germany}, ADDRESS = {Saarbr{\"u}cken, Germany}, PUBLISHER = {Max-Planck-Institut f{\"u}r Informatik}, MONTH = {March}, SERIES = {MPI Research Report}, VOLUME = {MPI-I-2002-2-007}, YEAR = {2002}, PAGES = {55--58}, } @PHDTHESIS{Maier2003, AUTHOR = {Maier, Patrick}, TITLE = {A Lattice-Theoretic Framework For Circular Assume-Guarantee Reasoning}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {July}, YEAR = {2003}, ABSTRACT = {We develop an abstract lattice-theoretic framework within which we study soundness and other properties of circular assume- guarantee (A-G) rules constrained by side conditions. We identify a particular side condition, non-blockingness, which admits an intelligible inductive proof of the soundness of circular A-G reasoning. Besides, conditional circular rules based on non-blockingness turn out to be complete in various senses and stronger than a large class of sound conditional A-G rules. In this respect, our framework enlightens the foundations of circular A-G reasoning. Due to its abstractness, the framework can be instantiated to many concrete settings. We show several known circular A-G rules for compositional verification to be instances of our generic rules. Thus, we do the circularity-breaking inductive argument once to establish soundness of our generic rules, which then implies soundness of all the instances without resorting to technically complicated circularity-breaking arguments for each single rule. In this respect, our framework unifies many approaches to circular A-G reasoning and provides a starting point for the systematic development of new circular A-G rules.}, } @INPROCEEDINGS{Maier2003a, AUTHOR = {Maier, Patrick}, EDITOR = {Gordon, Andrew D.}, TITLE = {Compositional Circular Assume-Guarantee Rules Cannot Be Sound and Complete}, BOOKTITLE = {Foundations of software science and computation structures : 6th International Conference, FOSSACS 2003}, PADDRESS = {Berlin, Germany}, ADDRESS = {Warsaw, Poland}, PUBLISHER = {Springer}, MONTH = {April}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2620}, ISBN = {3-540-00897-7}, YEAR = {2003}, PAGES = {343--357}, ABSTRACT = {Circular assume-guarantee reasoning is used for the compositional verification of concurrent systems. Its soundness has been studied in depth, perhaps because circularity makes it anything but obvious. In this paper, we investigate completeness. We show that compositional circular assume-guarantee rules cannot be both sound and complete.}, } @TECHREPORT{Maier2004, AUTHOR = {Maier, Patrick}, TITLE = {Intuitionistic LTL and a New Characterization of Safety and Liveness}, INSTITUTION = {Max-Planck-Institut f{\"u}r Informatik}, TYPE = {Research Report}, ADDRESS = {Stuhlsatzenhausweg 85, 66123 Saarbr{\"u}cken, Germany}, NUMBER = {MPI-I-2004-2-002}, PUBLISHER = {AG 2 - Ganzinger}, MONTH = {August}, ISBN = {0946-011X}, YEAR = {2004}, PAGES = {20}, ABSTRACT = {Classical linear-time temporal logic (LTL) is capable of specifying of and reasoning about infinite behaviors only. While this is appropriate for specifying non-terminating reactive systems, there are situations (e.g. assume-guarantee reasoning, run-time verification) when it is desirable to be able to reason about finite and infinite behaviors. We propose an interpretation of the operators of LTL on finite and infinite behaviors, which defines an intuitionistic temporal logic (ILTL). We compare the expressive power of LTL and ILTL. We demonstrate that ILTL is suitable for assume-guarantee reasoning and for expressing properties that relate finite and infinite behaviors. In particular, ILTL admits an elegant logical characterization of safety and liveness properties.}, } @INPROCEEDINGS{Maier2004, AUTHOR = {Maier, Patrick}, EDITOR = {Marcinkowski, Jerzy and Tarlecki, Andrzej}, TITLE = {Intuitionistic {LTL} and a New Characterization of Safety and Liveness}, BOOKTITLE = {Computer science logic : 18th International Workshop CSL 2004, 13th Annual Conference of the EACSL}, ORGANIZATION = {European Association for Computer Science Logic (EACSL)}, PADDRESS = {Berlin}, ADDRESS = {Karpacz, Poland}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3210}, YEAR = {2004}, PAGES = {295--309}, ABSTRACT = {Classical linear-time temporal logic (LTL) is capable of specifying of and reasoning about infinite behaviors only. While this is appropriate for specifying non-terminating reactive systems, there are situations (e.g. assume-guarantee reasoning, run-time verification) when it is desirable to be able to reason about finite and infinite behaviors. We propose an interpretation of the operators of LTL on finite and infinite behaviors, which defines an intuitionistic temporal logic (ILTL). We compare the expressive power of LTL and ILTL. We demonstrate that ILTL is suitable for assume-guarantee reasoning and for expressing properties that relate finite and infinite behaviors. In particular, ILTL admits an elegant logical characterization of safety and liveness properties.}, } @ARTICLE{makinson99, AUTHOR = {Makinson, David and van der Torre, Leendert W. N.}, JOURNAL = {Journal of Philosophical Logic}, TITLE = {Input-output logics}, ADDRESS = {Dordrecht, the Netherlands}, NUMBER = {4}, PUBLISHER = {Kluwer}, MONTH = {August}, VOLUME = {29}, ISBN = {0022-3611}, YEAR = {2000}, PAGES = {383--408}, ABSTRACT = {In a range of contexts, one comes across processes resembling inference, but where input propositions are not in general included among outputs, and the operation is not in any way reversible. Examples arise in contexts of conditional obligations, goals, ideals, preferences, actions, and beliefs. Our purpose is to develop a general theory of propositional input/output operations. Particular attention is given to the special case where outputs may be recycled as inputs.}, } @INPROCEEDINGS{makinson99b, AUTHOR = {Makinson, David and van der Torre, Leendert W. N.}, TITLE = {Input-output logics}, BOOKTITLE = {Proceedings of the 5th International Workshop on Deontic Logic in Computer Science (Deon-00),}, PADDRESS = {?}, ADDRESS = {Toulouse}, PUBLISHER = {?}, YEAR = {2001}, PAGES = {29}, ABSTRACT = {In a range of contexts, one comes across processes resembling inference, but where input propositions are not in general included among outputs, and the operation is not in any way reversible. Examples arise in contexts of conditional obligations, goals, ideals, preferences, actions, and beliefs. Our purpose is to develop a general theory of propositional input/output operations. Particular attention is given to the special case where outputs may be recycled as inputs.}, } @INPROCEEDINGS{malkis2006, AUTHOR = {Malkis, Alexander and Podelski, Andreas and Rybalchenko, Andrey}, EDITOR = {Barkaoui, Kamel and Cavalcanti, Ana and Cerone, Antonio}, TITLE = {Thread-Modular Verification is Cartesian Abstract Interpretation}, BOOKTITLE = {Theoretical Aspects of Computing - ICTAC 2006 : Third International Colloquium}, ORGANIZATION = {International University Macau}, PADDRESS = {Berlin, Germany}, ADDRESS = {Tunis, Tunisia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {4281}, ISBN = {978-3-540-48815-6}, DOI = {10.1007/11921240_13}, YEAR = {2006}, PAGES = {183--197}, ABSTRACT = {Verification of multithreaded programs is difficult. It requires reasoning about state spaces that grow exponentially in the number of concurrent threads. Successful verification techniques based on modular composition of over-approximations of thread behaviors have been designed for this task. These techniques have been traditionally described in assume-guarantee style, which does not admit reasoning about the abstraction properties of the involved compositional argument. Flanagan and Qadeer thread-modular algorithm is a characteristic representative of such techniques. In this paper, we investigate the formalization of this algorithm in the framework of abstract interpretation. We identify the abstraction that the algorithm implements; its definition involves Cartesian products of sets. Our result provides a basis for the systematic study of similar abstractions for dealing with the state explosion problem. As a first step in this direction, our result provides a characterization of a minimal increase in the precision of the Flanagan and Qadeer algorithm that leads to the loss of its polynomial complexity.}, } @UNPUBLISHED{malkis2006a, AUTHOR = {Malkis, Alexander and Podelski, Andreas and Rybalchenko, Andrey}, EDITOR = {Gopalakrishnan, Ganesh and O'Leary, John}, TITLE = {Thread-Modular Verification and Cartesian Abstraction}, MONTH = {August}, YEAR = {2006}, } @INPROCEEDINGS{MalkisPodelskiRybalchenkoSAS2007, AUTHOR = {Rybalchenko, Andrey}, TITLE = {Precise Thread-Modular Verification}, BOOKTITLE = {14th International Static Analysis Symposium (SAS 2007)}, PADDRESS = {Heidelberg}, ADDRESS = {Kongens Lyngby, Denmark}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, YEAR = {2007}, } @INPROCEEDINGS{Matthews92a, AUTHOR = {Matthews, Se{\'a}n}, EDITOR = {Yonezawa, A. and Smith, B. C.}, TITLE = {Reflection in a Logical System}, BOOKTITLE = {Proc.~IMSA '92 Workshop on Reflection and Meta-Level Architecture}, YEAR = {1992}, PAGES = {178--183}, NOTE = {Also available as Research Report MPI-I-92-250}, ABSTRACT = {I develop some of the theory of self-referential systems. I present the necessary semantic ideas, and combine this with work in proof theory, on the necessary properties of a proof predicate, to develop practical theories for reasoning about such systems. I propose to use this to exploit the idea of a reflection principle as a systematic way to extend such self-referential theories safely. I also try to relate theoretical points to practical concerns.}, } @INCOLLECTION{Matthews94b, AUTHOR = {Matthews, Se{\'a}n}, EDITOR = {Gabbay, Dov M.}, TITLE = {A Theory and its Metatheory in {$FS_0$}}, BOOKTITLE = {What is a logical system?}, CHAPTER = {13}, ADDRESS = {Oxford, UK}, PUBLISHER = {Oxford University Press}, YEAR = {1994}, PAGES = {329--354}, NOTE = {Also available as Research Report MPI-I-93-227, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken}, ABSTRACT = {Feferman has proposed {$FS_0$}, a theory of finitary inductive systems, as a framework theory suitable for various purposes, including practically reasoning both in and about encoded theories. I discuss here a formalisation of a sequent calculus presentation of classical propositional logic in {$FS_0$} and how this can be used for work in both the theory and the meta-theory. I illustrate the latter with a discussion of a proof of Gentzen's Hauptsatz.}, } @INPROCEEDINGS{Matthews96b, AUTHOR = {Matthews, Se{\'a}n}, EDITOR = {Paulson, Lawrence C.}, TITLE = {Implementing {$\textrm {FS}_0$} in {Isabelle}: Adding Structure at the Metalevel}, BOOKTITLE = {Design and Implementation of Symbolic Computation Systems (DISCO'96)}, ORGANIZATION = {DISCO}, PADDRESS = {Berlin, Germany}, ADDRESS = {Karlsruhe, Germany}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1128}, ISBN = {3540616977}, YEAR = {1996}, PAGES = {228--239}, ABSTRACT = {Often the theoretical virtue of simplicity in a theory does not fit with the practical necessities of use. An example of this is Feferman's FS0, a theory of inductive definitions which is very simple, but seems to lack all practical facilities. We present an implementation in the Isabelle generic theorem prover. We show that we can use the facilities available there to provide all the complex structuring facilities we need without compromising the simplicity of the original theory. The result is a thoroughly practical implementation. We further argue that it is unlikely that a custom implementation would be as effective.}, } @INPROCEEDINGS{Matthews97a, AUTHOR = {Matthews, Se{\'a}n}, EDITOR = {McCune, William}, TITLE = {A practical implementation of simple consequence relations using inductive definitions}, BOOKTITLE = {Proceedings of the 14th International Conference on Automated Deduction (CADE-14)}, ORGANIZATION = {Association for Automated Reasoning}, PADDRESS = {Berlin, Germany}, ADDRESS = {Townsville, Australia}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1249}, ISBN = {3-540-63104-6}, YEAR = {1997}, PAGES = {306--320}, ABSTRACT = {Logical frameworks such as the Edinburgh LF or Isabelle are not suitable for general metatheory, since they do not allow induction. On the other hand it is hard to encode a logic in an inductive definition-style framework so that it is usable for object theory. We propose a solution to this problem that borrows techniques from the type-theory tradition of logical frameworks for use with a language of inductive definitions, providing us with a notation suitable for practical object and metatheory both.}, } @INPROCEEDINGS{Matthews97b, AUTHOR = {Matthews, Se{\'a}n}, EDITOR = {Abadi, Mart{\'i}n and Ito, Takayasu}, TITLE = {Extending a logical framework with a modal connective for validity}, BOOKTITLE = {Proceedings of the 3rd Symposium on Theoretical Aspects of Computer Software (TACS-97)}, ORGANIZATION = {Tohoku University, ACM SIGACT, the Information Processing Society of Japan, the Japan Society of Software Science, Association for Symbolic Logic}, PADDRESS = {Berlin, Germany}, ADDRESS = {Sendai, Japan}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1281}, ISBN = {3-540-63388-X}, YEAR = {1997}, PAGES = {491--514}, ABSTRACT = {Logical frameworks, formal systems for programming consequence based proof systems, are well known. The notations that have been proposed are suited best to natural deduction style presentations based on truth consequence. We develop a conservative extension of a typical logical framework providing a modal connective which we can use to formalise validity. We argue that this extension is sensible, and provide example encodings of non-standard logics in its terms.}, } @INCOLLECTION{MatthewsSimpson96a, AUTHOR = {Matthews, Se{\'a}n and Simpson, Alex}, EDITOR = {Ursini, Aldo and Agilan{\`o}, Paolo}, TITLE = {Reflection using the derivability conditions}, BOOKTITLE = {Logic and Algebra}, TYPE = {Book}, ADDRESS = {New York, USA}, PUBLISHER = {Marcel Dekker}, EDITION = {1}, VOLUME = {180}, ISBN = {0824796063}, YEAR = {1996}, PAGES = {603--616}, ABSTRACT = {Reflection principles are a way to build non-conservative true extensions of a theory. However the application of a reflection principle needs a proof predicate, and the effort needed to provide this is so great as to be not really practical. We look at a possible way to avoid this effort by using, instead of a proof predicate, a predicate defined using only necessary `modal' properties. Surprisingly, we can produce powerful non-conservative extensions this way. But a reflection principle based on such a predicate is essentially weaker, and we also consider its limitations.}, } @INCOLLECTION{MatthewsSmaillBasin93a, AUTHOR = {Matthews, Se{\'a}n and Smaill, Alan and Basin, David A.}, EDITOR = {Huet, G. and Plotkin, G.}, TITLE = {Experience with {$FS_0$} as a Framework Theory}, BOOKTITLE = {Logical Environments}, ADDRESS = {Cambridge, UK}, PUBLISHER = {Cambridge University Press}, YEAR = {1993}, PAGES = {61--82}, NOTE = {Also available as Technical Report {MPI-I-92-214}}, ABSTRACT = {Feferman has proposed a system, ${FS_0}$, as an alternative framework for encoding logics and also for reasoning about those encodings. We have implemented a version of this framework and performed experiments that show that it is practical. Specifically, we describe a formalisation of predicate calculus and the development of an admissible rule that manipulates formulae with bound variables. This application will be of interest to researchers working with frameworks that use mechanisms based on substitution in the lambda calculus to implement variable binding and substitution in the declared logic directly. We suggest that meta-theoretic reasoning, even for a theory using bound variables, is not as difficult as is often supposed, and leads to more powerful ways of reasoning about the encoded theory.}, } @INPROCEEDINGS{Meter2009, AUTHOR = {Meter, Peter}, EDITOR = {Blubber, Bla and Bla, Blubber}, TITLE = {Just a test entry}, BOOKTITLE = {Booktitle}, PADDRESS = {Moon. Near Earth}, ADDRESS = {Moon Base}, NUMBER = {2}, PUBLISHER = {Space Spublishing Inc.}, SERIES = {Hello World From the Moon}, VOLUME = {1}, YEAR = {2009}, PAGES = {1001--1010}, NOTE = {Just a test entry - please ignore }, } @MASTERSTHESIS{Meyer-Diplom96, AUTHOR = {Meyer, Christoph}, TITLE = {Parallel Unit Resulting Resolution}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {February}, YEAR = {1996}, PAGES = {104}, ABSTRACT = {The term ``Parallel unit resulting resolution'' refers to a modified unit resulting resolution rule working on sets of substitutions. We modified the inference rule in order to investigate term indexing and to exploit parallelism in automated reasoning. Term indexing supports the construction of efficient automated reasoning systems by providing rapid access to first-order predicate calculus terms with specific properties. The theoretical background and the implementation of a theorem prover called {\sc Purr} which implements parallel unit resulting resolution as well as experiments with {\sc Purr} are presented in this thesis. The author addresses the reader interested in new indexing techniques and in distributed theorem proving.}, } @PHDTHESIS{Meyer-Diss, AUTHOR = {Meyer, Christoph}, TITLE = {Soft Typing for Clausal Inference Systems}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, YEAR = {1999}, } @INPROCEEDINGS{MNP-Ines, AUTHOR = {M{\"u}ller, Martin and Niehren, Joachim and Podelski, Andreas}, EDITOR = {Bidoit, Michel and Dauchet, Max}, TITLE = {Inclusion Constraints over Non-empty Sets of Trees}, BOOKTITLE = {Proceedings of the 7th International Joint Conference CAAP/FASE: Theory and practice of software development (TAPSOFT-97)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Lille, France}, PUBLISHER = {Springer}, MONTH = {April}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1214}, YEAR = {1997}, PAGES = {345--356}, } @ARTICLE{MNP:Constraints99, AUTHOR = {M{\"u}ller, Martin and Niehren, Joachim and Podelski, Andreas}, JOURNAL = {Constraints}, TITLE = {Ordering Constraints over Feature Trees}, ADDRESS = {Dordrecht, the Netherlands}, NUMBER = {1/2}, PUBLISHER = {Kluwer}, MONTH = {January}, VOLUME = {5}, ISBN = {1383-7133}, YEAR = {2000}, PAGES = {7--41}, ABSTRACT = { Feature trees have been used to accommodate records in constraint programming and record like structures in computational linguistics. Feature trees model records and subtree selection constraints yield extensible and modular record descriptions. We introduce the constraint system \FEAT\ of ordering constraints interpreted over feature trees. Under the view that feature trees represent symbolic information, the $\leq$-relation corresponds to the information ordering (``carries less information than''). We present a polynomial algorithm that decides the satisfiability of conjunctions of positive and negative information ordering constraints over feature trees. Our results include algorithms for the satisfiability problem and the entailment problem of \FEAT\ in time $O(n^3)$. We also show that \FEAT\ has the independence property (and are thus able to handle negative conjuncts via entailment). Furthermore, we reduce the satisfiability problem of D\"orre's weak-subsumption constraints to the satisfiability problem of \FEAT. This improves the complexity bound for solving weak subsumption constraints from $O(n^5)$ to $O(n^3)$.}, } @INCOLLECTION{mod-modal, AUTHOR = {Basin, David A. and Krieg-Br{\"u}ckner, Bernd}, EDITOR = {Astesiano, Egidio and Kreowski, H.-J. and Krieg-Br{\"u}ckner, B.}, TITLE = {Formalization of the Development Process}, BOOKTITLE = {Algebraic foundations of systems specification}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, ISBN = {3-540-63772-9}, YEAR = {1999}, PAGES = {521--562}, } @MASTERSTHESIS{Mohr95, AUTHOR = {Mohr, Erik}, TITLE = {Resolution-Based Calculi for Modal Logics}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1995}, ABSTRACT = {Based on different translation approaches from first-order modal logic into first-order predicate logic we develop several kinds of resolution-based calculi with additional theory clauses, inference rules or special unification algorithms. Especially the methods presented for the semi-functional and functional approaches lead to limited branching in the proof search tree and therefore to smaller sets of generated clauses. In all cases soundness and (refutation) completeness proofs for these calculi are provided. The methods have been applied to serial modal logics (i.e. modal logics containing the so-called axiom D) with constant, (and partially) varying, increasing and decreasing domain structures and any combination of the following modal logic axioms: T, B, 4 and 5.}, } @INPROCEEDINGS{MP-SARA02, AUTHOR = {Mukhopadhyay, Supratik and Podelski, Andreas}, EDITOR = {Koenig, Sven and Holte, Robert C.}, TITLE = {An Algebraic Framework for Abstract Model Checking}, BOOKTITLE = {Abstraction, reformulation, and approximation : 5th International Symposium, SARA 2002}, PADDRESS = {Berlin, Germany}, ADDRESS = {Montreal}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2371}, ISBN = {3-540-43941-2}, YEAR = {2002}, PAGES = {152--169}, } @INPROCEEDINGS{MuellerNiehrenPodelski97a, AUTHOR = {M{\"u}ller, Martin and Niehren, Joachim and Podelski, Andreas}, EDITOR = {Smolka, Gert}, TITLE = {Ordering Constraints over Feature Trees}, BOOKTITLE = {Proceedings of the 3rd International Conference on Principles and Practice of Constraint Programming (CP-97)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Linz, Austria}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1330}, ISBN = {3-540-63753-2}, YEAR = {1997}, PAGES = {549--562}, } @PHDTHESIS{Mukhopadhyay-Thesis-2001, AUTHOR = {Mukhopadhyay, Supratik}, TITLE = {A Uniform Constraint-based Framework for the Verification of Infinite State Systems}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {May}, YEAR = {2001}, } @INPROCEEDINGS{Mukhopadhyay2000, AUTHOR = {Mukhopadhyay, Supratik and Podelski, Andreas}, EDITOR = {Lloyd, John W. and Dahl, Ver{\'o}nica and Furbach, Ulrich and Kerber, Manfred and Lau, Kung-Kiu and Palamidessi, Catuscia and Pereira, Lu{\'i}s Moniz and Sagiv, Yehoshua and Stuckey, Peter J.}, TITLE = {Model Checking for Timed Logic Processes}, BOOKTITLE = {Proceedings of the 1st International Conference on Computational Logic}, PADDRESS = {Berlin, Germany}, ADDRESS = {Imperial College, London, UK}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1861}, YEAR = {2000}, PAGES = {598--612}, } @INPROCEEDINGS{MukhopadhyayPodelski2001, AUTHOR = {Mukhopadhyay, Supratik and Podelski, Andreas}, EDITOR = {Ramakrishnan, I.V.}, TITLE = {Constraint Database Models Characterizing Timed Bisimilarity}, BOOKTITLE = {Proceedings of the 3rd International Symposium on Practical Aspects of Declarative Languages}, ORGANIZATION = {Compulog Americas}, PADDRESS = {Berlin, Germany}, ADDRESS = {Las Vegas, USA}, PUBLISHER = {Springer}, MONTH = {March}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1990}, YEAR = {2001}, PAGES = {245--258}, ABSTRACT = {The problem of deciding timed bisimilarity has received increasing attention; it is important for verification of timed systems. Using a characterization of timed bisimilarity in terms of models of constraint databases, we present to our knowledge, the first \emph{local}, \emph{symbolic algorithm} for deciding timed bisimilarity; previous algorithms were based on a finite, but prohibitively large, abstraction (the region graph or the full backward stable graph). Our algorithm uses XSB-style tabling with constraints. Our methodology is more general than those followed in the previous approaches in the sense that our algorithm can be used to decide whether two timed systems are \emph{alternating timed bisimilar}. }, } @INPROCEEDINGS{MukhopadhyayPodelskiErshov2001, AUTHOR = {Mukhopadhyay, Supratik and Podelski, Andreas}, EDITOR = {Zamulin, Alexandre and Broy, Manfred and Bjorner, Dines}, TITLE = {Accurate Widenings and Boundedness Properties of Timed Systems}, BOOKTITLE = {Perspectives of System Informatics: 4th International Andrei Ershov Memorial Conference}, PADDRESS = {Berlin, Germany}, ADDRESS = {Novosibirsk, Russia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2244}, ISBN = {3-540-43075-X}, YEAR = {2001}, PAGES = {79--94}, } @INPROCEEDINGS{MukhopadhyayPodelskiFSTTCS1999, AUTHOR = {Mukhopadhyay, Supratik and Podelski, Andreas}, EDITOR = {Ramanujam, R and Raman, V.}, TITLE = {Beyond Region Graphs: Symbolic Forward Analysis of Timed Automata}, BOOKTITLE = {Proceedings of the 19th Conference on Foundations of Software Technology and Theoretical Computer Science (FST\&TCS-99)}, ORGANIZATION = {IARCS}, PADDRESS = {Berlin, Germany}, ADDRESS = {Chennai, India}, PUBLISHER = {Springer}, MONTH = {December}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1738}, ISBN = {3-540-66836-5}, YEAR = {1999}, PAGES = {232--244}, } @MASTERSTHESIS{Naumann-Diplom97, AUTHOR = {Naumann, Stefan}, TITLE = {{Integration des automatischen Beweisers {SPASS} in die mathematische Assistenzumgebung {OMEGA}}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1997}, } @INPROCEEDINGS{NiehrenMuellerTalbot_LICS1999, AUTHOR = {Talbot, Jean-Marc and Niehren, Joachim and M{\"u}ller, Martin}, EDITOR = {Longo, Giuseppe}, TITLE = {Entailment of Atomic Set Constraints is {PSPACE}-Complete}, BOOKTITLE = {Proceedings of the 14th Annual IEEE Symposium on Logic in Computer Science (LICS-99)}, ORGANIZATION = {IEEE Computer Society}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Trento, Italy}, PUBLISHER = {IEEE}, YEAR = {1999}, PAGES = {285--294}, } @INPROCEEDINGS{NieuwenhuisHillenbrandRiazanovVoronkov2001, AUTHOR = {Nieuwenhuis, Robert and Hillenbrand, Thomas and Riazanov, Alexandre and Voronkov, Andrei}, EDITOR = {Gor{\'e}, Rajeev and Leitsch, Alexander and Nipkow, Tobias}, TITLE = {On the Evaluation of Indexing Techniques for Theorem Proving}, BOOKTITLE = {Automated reasoning : First International Joint Conference, IJCAR 2001}, PADDRESS = {Berlin, Germany}, ADDRESS = {Siena, Italy}, PUBLISHER = {Springer}, MONTH = {June}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2083}, ISBN = {3-540-42254-5}, YEAR = {2001}, PAGES = {257--271}, } @INPROCEEDINGS{NiSe01esop, AUTHOR = {Nielson, Flemming and Seidl, Helmut}, EDITOR = {Hussmann, Heinrich}, TITLE = {Control-Flow Analysis in Cubic Time}, BOOKTITLE = {Proceedings of the 10th European Symposium on Programming (ESOP-01) held as part of the Joint European Conferences on Theory and Practice of Software (ETAPS-01)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Genova, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2028}, ISBN = {3-540-41862-8}, YEAR = {2001}, PAGES = {252--268}, } @ARTICLE{NivatPodelski97, AUTHOR = {Nivat, Maurice and Podelski, Andreas}, JOURNAL = {SIAM Journal on Computing}, TITLE = {Minimal Ascending and Descending Tree Automata}, NUMBER = {1}, VOLUME = {26}, YEAR = {1997}, PAGES = {39--58}, } @TECHREPORT{NivelleYevgeny2004, AUTHOR = {de Nivelle, Hans and Kazakov, Yevgeny}, TITLE = {Resolution Decision Procedures for the Guarded Fragment with Transitive Guards}, INSTITUTION = {Max-Planck-Institut f{\"u}r Informatik}, TYPE = {Research Report}, ADDRESS = {Stuhlsatzenhausweg 85, 66123 Saarbr{\"u}cken, Germany}, NUMBER = {MPI-I-2004-2-001}, PUBLISHER = {AG 2 - Ganzinger}, MONTH = {April}, ISBN = {0946-011X}, YEAR = {2004}, PAGES = {32}, } @PHDTHESIS{Nonnengart-Dissertation, AUTHOR = {Nonnengart, Andreas}, TITLE = {A Resolution-Based Calculus for Temporal Logics}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {December}, YEAR = {1995}, ABSTRACT = {The increasing interest in applying temporal logics in various areas of computer science requires the development of efficient means that allow to reason within such logics. Usually this is realized by an implementable calculus and indeed remarkable progress has been made in the last two decades. The approaches developed so far can be roughly divided into two main categories: Either known techniques are extended to cope with the temporal logic syntax, or translation techniques into predicate logic are defined which allow to exploit already existing calculi. The former approach has the advantage that derivations remain within the temporal logic syntax, whereas the latter approach benefits from many years (in fact decades) of experience gained in classical logic theorem proving. The approach proposed in this work is based on a particular translation method into classical first-order predicate logic which utilizes certain interesting translational invariants. The reader is assumed to have detailed knowledge of automated theorem proving and formal logic, in particular classical first-order predicate logic. Although the introduction of modal and temporal logics is fairly self-contained at least some knowledge of these logic areas would be quite helpful.}, } @ARTICLE{Nonnengart1998, AUTHOR = {Nonnengart, Andreas}, JOURNAL = {Logic Journal of the IGPL}, TITLE = {Modal Frame Characterization by Way of Auxiliary Modalities}, NUMBER = {6}, PUBLISHER = {Oxford University Press}, MONTH = {November}, VOLUME = {6}, ISBN = {1368-9894}, YEAR = {1998}, PAGES = {875--899}, ABSTRACT = {In modal logics we are interested in classes of frames that characterize the logic under consideration. Such classes are usually distinguished by their respective frame properties. In general these characterizations are not unique and it is desirable to find a strongest possible. In this article an approach is presented which helps in this respect. It allows us to transform a given background theory into one which is more general and which modal logics cannot distinguish from the former because of their syntactic and semantic restrictions. The underlying technique is based on the idea to find conservative extensions of a given logic whose frame properties allow us to extract significantly stronger characterizations of the original logic.}, } @INPROCEEDINGS{nonnengart93a, AUTHOR = {Nonnengart, Andreas}, EDITOR = {Bajcsy, R.}, TITLE = {First-Order Modal Logic Theorem Proving and Functional Simulation}, BOOKTITLE = {Proc.~13th Intern.~Joint Conference on Artificial Intelligence (IJCAI '93)}, PADDRESS = {San Mateo, CA}, ADDRESS = {Chambery, France}, PUBLISHER = {Morgan Kaufmann}, VOLUME = {1}, YEAR = {1993}, PAGES = {80--85}, ABSTRACT = {We propose a translation approach from modal logics to first-order predicate logic which combines advantages from both, the (standard) relational translation and the (rather compact) functional translation method and avoids many of their respective disadvantages (exponential growth versus equality handling).\\ In particular in the application to serial modal logics it allows considerable simplifications such that often even a simple unit clause suffices in order to express the accessibility relation properties.\\ Although we restrict the approach here to first-order modal logic theorem proving it has been shown to be of wider interest, as e.g.~sorted logic or terminological logic.}, } @UNPUBLISHED{Nonnengart98, AUTHOR = {Nonnengart, Andreas}, TITLE = {Strong Skolemization}, MONTH = {September}, YEAR = {2001}, PAGES = {18}, NOTE = {Journal version of the corresponding technical report. Submitted for publication}, ABSTRACT = {Skolemization is a means to eliminate existential quantifiers within predicate logic sentences by replacing existentially quantified variables with Skolem function applications. The arguments of such Skolem functions are variables that are quantified outside the sub-formula under consideration. In this article a skolemization technique is introduced which abstracts from some of the Skolem function arguments. It turns out that the result obtained this way is usually more general than what can be achieved from standard (classical) Skolemization techniques. From a theorem prover's point of view such generalizations often lead to a reduction of both search space and proof length. }, } @INPROCEEDINGS{NonnengartCADE96, AUTHOR = {Nonnengart, Andreas}, EDITOR = {McRobbie, M. A. and Slaney, J. K.}, TITLE = {Resolution-Based Calculi for Modal and Temporal Logics}, BOOKTITLE = {Proceedings of the 13th International Conference on Automated Deduction (CADE-13)}, ORGANIZATION = {CADE Incorporated}, PADDRESS = {Berlin, Germany}, ADDRESS = {New Brunswick, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1104}, ISBN = {3-540-61511-3}, YEAR = {1996}, PAGES = {598--612}, ABSTRACT = {In this paper a technique is presented which provides us with a means to develop resolution-based calculi for (first-order) modal and temporal logics. The approach is based on three parts: A special translation technique from modal and temporal logic formulae into classical predicate logic, a certain kind of saturation technique which is to be applied to given background theories, and an extraction of either suitable ``simpler'' background theories or logic-specific inference rules. The former is interesting in case existing classical logic theorem provers are to be utilized; the latter gains importance if one is prepared to extend theorem provers that are already at hand.}, } @INPROCEEDINGS{NonnengartJELIA94, AUTHOR = {Nonnengart, Andreas}, EDITOR = {MacNish, Craig and Pearce, David and Pereira, Lu{\'i}s Moniz}, TITLE = {How to Use Modalities and Sorts in Prolog}, BOOKTITLE = {Logics in Artificial Intelligence: Proceedings of the JELIA'94}, PADDRESS = {Berlin, Germany}, ADDRESS = {York, UK}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {838}, YEAR = {1994}, PAGES = {365--378}, ABSTRACT = {Standard logic programming languages like Prolog lack the possibility of dealing with modalities and/or sorts. A first idea how to overcome this problem (and that without changing anything on Prolog itself) would be to apply the well-known relational translation approaches from modal and sorted logic into first-order predicate logic and to feed this translation result into Prolog. This, however, leads into other problems: firstly, the transformed problem is usually of much bigger size (number of clauses) than the original one and, secondly, very often it is not even in Horn form anymore. In this paper a translation approach is proposed which avoids both of these problems, i.e.\ the number of clauses after translation is exactly as big as it would have been if we simply ignored the modal operators and sort restrictions and, also, the result is in Horn form provided it was already before (modulo modal operators and sorts).}, } @INCOLLECTION{NonnengartOhlbach92a, AUTHOR = {Nonnengart, Andreas and Ohlbach, Hans J{\"u}rgen}, EDITOR = {Bl{\"a}sius, K. H. and B{\"u}rckert, Hans-J{\"u}rgen}, TITLE = {{Modal- und Temporallogik}}, BOOKTITLE = {Deduktionssysteme - Automatisierung des logischen Denkens}, CHAPTER = {VII}, ADDRESS = {M{\"u}nchen, Germany}, PUBLISHER = {Oldenbourg}, EDITION = {2}, ISBN = {3-486-22033-0}, YEAR = {1992}, PAGES = {239--284}, } @INCOLLECTION{NonnengartOhlbachGabbay2001, AUTHOR = {Nonnengart, Andreas and Ohlbach, Hans J{\"u}rgen and Gabbay, Dov M.}, EDITOR = {Robinson, Alan and Voronkov, Andrei}, TITLE = {Encoding two-valued non-classical logics in classic logic}, BOOKTITLE = {Handbook of Automated Reasoning}, CHAPTER = {21}, ADDRESS = {Amsterdam, the Netherlands}, PUBLISHER = {Elsevier}, MONTH = {January}, VOLUME = {2}, YEAR = {2001}, PAGES = {1403--1486}, } @UNPUBLISHED{NonnengartOhlbachSzalas98, AUTHOR = {Nonnengart, Andreas and Ohlbach, Hans J{\"u}rgen and Szalas, Andrzej}, TITLE = {Quantifier Elimination for Second-Order Predicate Logic}, MONTH = {January}, YEAR = {2001}, PAGES = {21}, NOTE = {To appear in \emph{Logic, Language and Reasoning. Essays in honour of Dov Gabbay, Part I, Kluwer Academic Press}}, } @INPROCEEDINGS{NonnengartRockWeidenbach98, AUTHOR = {Nonnengart, Andreas and Rock, Georg and Weidenbach, Christoph}, EDITOR = {Kirchner, Claude and Kirchner, H{\'e}l{\`e}ne}, TITLE = {On Generating Small Clause Normal Forms}, BOOKTITLE = {Proceedings of the 15th International Conference on Automated Deduction (CADE-98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Lindau, Germany}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1421}, ISBN = {3-540-64675-2}, YEAR = {1998}, PAGES = {397--411}, ABSTRACT = {In this paper we focus on two powerful techniques to obtain compact clause normal forms: Renaming of formulae and refined Skolemization methods. We illustrate their effect on various examples. By an exhaustive experiment of all first-order TPTP problems, it shows that our clause normal form transformation yields fewer clauses and fewer literals than the methods known and used so far. This often allows for exponentially shorter proofs and, in some cases, it makes it even possible for a theorem prover to find a proof where it was unable to do so with more standard clause normal form transformations.}, } @INCOLLECTION{NonnengartSzalas1999, AUTHOR = {Nonnengart, Andreas and Szalas, Andrzej}, EDITOR = {Orlowska, Ewa}, TITLE = {A Fixpoint Approach to Second-Order Quantifier Elimination with Applications to Correspondence Theory}, BOOKTITLE = {Logic at Work: Essays Dedicated to the Memory of Helena Rasiowa}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, MONTH = {January}, SERIES = {Studies in Fuzziness and Soft Computing}, VOLUME = {24}, ISBN = {3-7908-1164-5}, YEAR = {1999}, PAGES = {18}, } @INCOLLECTION{NonnengartWeidenbach2001handbook, AUTHOR = {Nonnengart, Andreas and Weidenbach, Christoph}, EDITOR = {Robinson, Alan and Voronkov, Andrei}, TITLE = {Computing small clause normal forms}, BOOKTITLE = {Handbook of Automated Reasoning}, CHAPTER = {6}, ADDRESS = {Amsterdam, the Netherlands}, PUBLISHER = {Elsevier}, MONTH = {January}, VOLUME = {1}, YEAR = {2001}, PAGES = {335--367}, } @PHDTHESIS{Ohlbach88, AUTHOR = {Ohlbach, Hans J{\"u}rgen}, TITLE = {A Resolution Calculus for Modal Logics}, SCHOOL = {Universit{\"a}t Kaiserslautern}, TYPE = {Doctoral dissertation}, YEAR = {1988}, } @ARTICLE{Ohlbach91a, AUTHOR = {Ohlbach, Hans J{\"u}rgen}, JOURNAL = {Journal of Logic and Computation}, TITLE = {Semantics Based Translation Methods for Modal Logics}, NUMBER = {5}, PUBLISHER = {Oxford University Press}, VOLUME = {1}, ISBN = {0955-792X}, YEAR = {1991}, PAGES = {691--746}, ABSTRACT = {A general framework for translating logical formulae from one logic into another logic is presented. The framework is instantiated with two different approaches to translating modal logic formulae into predicate logic. The first one, the well known relational translation makes the modal logic's possible worlds structure explicit by introducing a distinguished predicate symbol to represent the accessibility relation. In the second approach, the functional translation method, paths in the possible worlds structure are represented by compositions of functions which map worlds to accessible worlds. On the syntactic level this means that every flexible symbol is parametrized with particular terms denoting whole paths from the initial world to the actual world. The target logic for the translation is a first-order many-sorted logic with built in equality. Therefore the source logic may also be first-order many-sorted with built in equality. Furthermore flexible function symbols are allowed. The modal operators may be parametrized with arbitrary terms and particular properties of the accessibility relation may be specified within the logic itself.}, } @ARTICLE{Ohlbach92a, AUTHOR = {Ohlbach, Hans J{\"u}rgen}, JOURNAL = {KI}, TITLE = {{Logic Engineering: Konstruktion von Logiken}}, VOLUME = {3}, YEAR = {1992}, PAGES = {34--38}, NOTE = {Special Issue on Logic}, ABSTRACT = {In diesem Beitrag wird gezeigt, wie man monotone zweiwertige Logiken mit Hilfe von Hilbertkalk{\"u}len spezifizieren und diese Spezifikation automatisch in einem Compiler transformieren kann, der Formeln dieser Logik in normale Pr{\"a}dikatenlogik {\"u}bersetzt. Es ist damit unn{\"o}tig geworden, spezielle Kalk{\"u}le f{\"u}r diese Logken zu entwickeln. Alle f{\"u}r Pr{\"a}dikatenlogik entwickelten Methoden -- Kalk\"ule, automatische Beweiser, logische Programmiersprachen, KL-ONE basierte Wissensrepr\"astenationssprachen, Defaultmechanismen und so weiter -- sind dann auch f\"ur die neu definierten Logiken anwendbar. Damit steht eine Methodik zur Verf\"ugung, um komplexe Logiken f\"ur Anwednungen in der KI ma{\"s}zuschneidern, ohne die notwendingen Inferenzverfahren wieder neu erfinden zu m\"ussen.}, } @INPROCEEDINGS{Ohlbach93a, AUTHOR = {Ohlbach, Hans J{\"u}rgen}, EDITOR = {Kobsa, Alfred}, TITLE = {{Ein kurzes Tutorial {\"u}ber funktionale {\"U}bersetzung von Modallogik nach Pr{\"a}dikatenlogik}}, BOOKTITLE = {Bericht Nr. 15/93: Recommendations for Extensions to BGP-MS}, TYPE = {Tutorial}, PADDRESS = {Konstanz, Germany}, ADDRESS = {?}, PUBLISHER = {Universit{\"a}t Konstanz, FB Informationswissenschaft}, YEAR = {1993}, PAGES = {19--26}, ABSTRACT = {In diesem Bericht werden die wesentlichen Punkte gekl{\"a}rt, die f{\"u}r Anwender der funktionalen {\"U}bersetzung von Modal- nach Pr{\"a}dikatenlogik wichtig sind.}, } @ARTICLE{Ohlbach93c, AUTHOR = {Ohlbach, Hans J{\"u}rgen}, JOURNAL = {Bulletin of the Interest Group in Propositional and Predicate Logics (IGPL)}, TITLE = {Translation Methods for Non-Classical Logics: An Overview}, NUMBER = {1}, VOLUME = {1}, YEAR = {1993}, PAGES = {69--90}, NOTE = {A short version appeared in Proc.~LPAR '93, vol. 698 of Lecture Notes in Computer Science, pp.~253-264, Springer-Verlag, Berlin. Also available as Technical Report MPI-I-93-225}, ABSTRACT = {This paper gives an overview on translation methods we have developed for non-classical logics, in particular for modal logics.\ Optimized `functional' and semi-functional translation into predicate logic is described. Using normal modal logic as an intermediate logic, other logics can be translated into predicate logic as well. As an example, the translation of modal logic of graded modalities is sketched. In the second part of the paper it is shown how to translate Hilbert axioms into properties of the semantic structure and vice versa, i.e. we can automate important parts of correspondence theory. The exact formalisms and the soundness and completeness proofs can be found in the original papers.}, } @UNPUBLISHED{Ohlbach95a, AUTHOR = {Ohlbach, Hans J{\"u}rgen}, TITLE = {Clause Killer Transformations}, YEAR = {1995}, NOTE = {Submitted to the Journal of Automated Reasoning}, ABSTRACT = {It is shown how self resolving clauses like the transitivity clause or the condensed detachment clause can be deleted from the clause set by generating not all, but sufficiently many resolvents with the self resolving clause. Using this technique I found dramatic improvements of the performance of automated theorem provers on extremely hard problems. As by--products we get a method for encoding some axioms in Prolog which normally would generate loops, and we get a method for parallelizing some closure computation algorithms.}, } @UNPUBLISHED{Ohlbach95b, AUTHOR = {Ohlbach, Hans J{\"u}rgen}, TITLE = {Boolean Algebras with Functions - Correspondence, Completeness and Quantifier Elimination}, YEAR = {1995}, NOTE = {Submitted to IJCAI 95}, ABSTRACT = {It is shown how axiomatic specifications of Boolean Algebras with extra functions as well as propositional extension of standard propositional logic can be transformed and simplified using syntactic methods, in particular quantifier elimination algorithms for second--order predicate logic. This enables us to exploit representation theorems and model theoretic semantics for these algebras and logics in such a way that for special instances of these systems, i.e. particular algebras and particular logics the corresponding specializations on the semantic side can be computed automatically. Special cases of the results of this paper are the theorem proving aspects of J{\'o}nsson and Traski's representation theorem for Boolean Algebras with operators, completeness of different possible worlds semantics for modal logics and a clarification of the correlation between correspondence and completeness in modal logics. }, } @INPROCEEDINGS{Ohlbach96-CADE-13, AUTHOR = {Ohlbach, Hans J{\"u}rgen}, EDITOR = {McRobbie, M. A. and Slaney, J. K.}, TITLE = {{SCAN}-Elimination of Predicate Quantifiers}, BOOKTITLE = {Proceedings of the 13th International Conference on Automated Deduction (CADE-13)}, ORGANIZATION = {AT\&T, Bell Labs, Lucent, IEEE, CADE inc}, TYPE = {Full paper}, PADDRESS = {Berlin, Germany}, ADDRESS = {New Brunswick, New Jersey, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1104}, ISBN = {3-540-61-511-3}, YEAR = {1996}, PAGES = {161--165}, } @PHDTHESIS{OhlbachHabil1993, AUTHOR = {Ohlbach, Hans J{\"u}rgen}, TITLE = {Thema der Antrittsvorlesung: Transformation logischer Systeme}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Habilitation thesis}, MONTH = {December}, YEAR = {1993}, } @INPROCEEDINGS{OhlbachHerzig91a, AUTHOR = {Ohlbach, Hans J{\"u}rgen and Herzig, A.}, TITLE = {Parameter Structures for Parametrized Modal Operators}, BOOKTITLE = {Proc.~Intern.~Joint Conference on Artificial Intelligence (IJCAI'91)}, PADDRESS = {San Mateo, CA}, ADDRESS = {Sydney, Australia}, PUBLISHER = {Morgan Kaufmann}, YEAR = {1991}, PAGES = {512--517}, ABSTRACT = {The parameters of the parametrized modal operators $[p]$ and $\Diamond{p}$ usually represent agents (in the epistemic interpretation) or actions (in the dynamic logic interpretation) or the like. In this paper the application of the idea of parametrized modal operators is extended in two ways: First of all a modified neighbourhood semantics is defined which permits among others the interpretation of the parameters as probability values. A formula $[.5]F$ may for example express the fact that in at least $50\%$ of all cases (worlds) $F$ holds. These probability values can be numbers, qualitative descriptions and even arbitrary terms. Secondly a general theory of the parameters and in particular of the characteristic operations on the parameters is developed which unifies for example the multiplication of numbers in the probabilistic interpretation of the parameters and the sequencing of actions in the dynamic logic interpretation.}, } @TECHREPORT{OhlbachKoehler96, AUTHOR = {Ohlbach, Hans J{\"u}rgen and Koehler, Jana}, TITLE = {Reasoning about Sets via Atomic Decomposition}, INSTITUTION = {International Computer Science Institute}, TYPE = {Technical Report}, ADDRESS = {Berkeley, CA}, NUMBER = {TR-96-31}, YEAR = {1996}, PAGES = {39}, NOTE = {Submitted to the \emph{AI Journal}}, ABSTRACT = {We introduce a new technique that translates cardinality information about finite sets into simple arithmetic terms thereby enabling a system to reason about such set cardinalities by solving arithmetic equation problems. The atomic decomposition technique separates a collection of sets into smallest mutually disjoint components (``atoms'') such that the cardinality of the sets are just the sum of the cardinalities of their atoms. With this idea, it is possible to have languages combining arithmetic formulas with set terms and to translate the formulas of this combined logic into pure arithmetical formulas. As a particular application, we show how this technique yields new inference procedures for concept languages with so-called number restriction operators. }, } @INPROCEEDINGS{OhlbachLPAR93, AUTHOR = {Ohlbach, Hans J{\"u}rgen}, EDITOR = {Voronkov, A.}, TITLE = {Optimized Translation of Multi Modal Logic into Predicate Logic}, BOOKTITLE = {Proceedings of the 4th International Conference on Logic Programming and Automated Reasoning (LPAR'93)}, PADDRESS = {Berlin, Germany}, ADDRESS = {St. Petersburg, Russia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {698}, YEAR = {1993}, PAGES = {253--264}, } @ARTICLE{OhlbachSchmidt97, AUTHOR = {Ohlbach, Hans J{\"u}rgen and Schmidt, Renate A.}, JOURNAL = {Journal of Logic and Computation}, TITLE = {Functional Translation and Second-Order Frame Properties of Modal Logics}, NUMBER = {5}, PUBLISHER = {Oxford University Press}, MONTH = {October}, VOLUME = {7}, ISBN = {0955-792X}, YEAR = {1997}, PAGES = {581--603}, NOTE = {Also available as Research Report MPI-I-95-2-002}, ABSTRACT = {Normal modal logics can be defined axiomatically as Hilbert systems, or semantically in terms of Kripke's possible worlds and accessibility relations. Unfortunately there are Hilbert axioms which do not have corresponding first-order properties for the accessibility relation. For these logics the standard semantics-based theorem proving techniques, in particular, the relational translation into first-order predicate logic, do not work. There is an alternative translation, the so-called functional translation, in which the accessibility relations are replaced by certain terms which intuitively can be seen as functions mapping worlds to accessible worlds. In this paper we show that from a certain point of view this functional language is more expressive than the relational language, and that certain second-order frame properties can be mapped to first-order formulae expressed in the functional language. Moreover, we show how these formulae can be computed automatically from the Hilbert axioms. This extends the applicability of the functional translation method. }, } @INPROCEEDINGS{OhlbachSchmidtHustadt95b, AUTHOR = {Ohlbach, Hans J{\"u}rgen and Schmidt, Renate A. and Hustadt, Ullrich}, EDITOR = {Borgida, A. and Lenzerini, M. and Nardi, D. and Nebel, B.}, TITLE = {Symbolic Arithmetical Reasoning with Qualified Number Restrictions}, BOOKTITLE = {Proceedings of International Workshop on Description Logics'95}, PADDRESS = {Rome}, ADDRESS = {Rome, Italy}, NUMBER = {07.95}, PUBLISHER = {Dipartimento di Informatica e Sistemistica, Univ. degli studia di Roma}, MONTH = {May}, SERIES = {Rap.}, YEAR = {1995}, PAGES = {89--95}, ABSTRACT = {Many inference systems used for concept description logics are constraint systems that employ tableaux methods. These have the disadvantage that for reasoning with qualified number restrictions $n$ new constant symbols are generated for each concept of the form $(\geq n \ R \ C)$. In this paper we present an alternative method that avoids the generation of constants and uses a restricted form of symbolic arithmetic considerably different from the tableaux method. The method we use is introduced in Ohlbach, Schmidt and Hustadt (1995) for reasoning with graded modalities. We exploit the exact correspondence between the concept description language $\cal ALCN$ and the multi-modal version of the graded modal logic $\overline{\mbox{\bf K}}$ and show how the method can be applied to $\cal ALCN$ as well. This paper is a condensed version of Ohlbach et al.\ (1995). We omit proofs and much of the technical details, but we include some examples.}, } @INCOLLECTION{OhlbachSchmidtHustadt96, AUTHOR = {Ohlbach, Hans J{\"u}rgen and Schmidt, Renate A. and Hustadt, Ullrich}, EDITOR = {Wansing, H.}, TITLE = {Translating Graded Modalities into Predicate Logic}, BOOKTITLE = {Proof Theory of Modal Logic}, INSTITUTION = {Max-Planck-Institut f{\"u}r Informatik}, ADDRESS = {Dordrecht, The Netherlands}, PUBLISHER = {Kluwer}, SERIES = {Studies in Applied Logic Series}, ISBN = {0-7923-4120-1}, YEAR = {1996}, PAGES = {253--291}, NOTE = {Also available as Research Report MPI-I-95-2-008}, ABSTRACT = {In the logic of graded modalities it is possible to talk about sets of finite cardinality. Various calculi exist for graded modal logics and all generate vast amounts of case distinctions. In this paper we present an optimized translation from graded modal logic into many-sorted predicate logic. This translation has the advantage that in contrast to known approaches our calculus enables us to reason with cardinalities of sets symbolically. In many cases the length of proofs for theorems of this calculus is independent of the cardinalities. The translation is sound and complete.}, } @INPROCEEDINGS{OhlbachSiekmann91a, AUTHOR = {Ohlbach, Hans J{\"u}rgen and Siekmann, J{\"o}rg H.}, EDITOR = {Lassez, J. L. and Plotkin, Gordon}, TITLE = {The {Markgraf Karl} Refutation Procedure}, BOOKTITLE = {Computational Logic, Essays in Honor of Alan Robinson}, PADDRESS = {Cambridge, USA}, ADDRESS = {?}, PUBLISHER = {MIT Press}, YEAR = {1991}, PAGES = {41--112}, ABSTRACT = {The goal of the {\em MKRP project} is the development of a theorem prover which can be used as an inference engine in various applications, in particular it should be capable of proving significant mathematical theorems. Our first implementation, the {\em Markgraf Karl Refutation Procedure (MKRP)} realizes some of the ideas we have developed to this end. It is a general purpose resolution based deduction system that exploits the representation of formulae as a graph (clause graph). The main features are its well tailored selection components, heuristics and control mechanisms for guiding the search for a proof. mechanisms for guiding the search for a proof. This paper gives an overview of the system. It summarizes and evaluates our experience with the system in particular, and the logics we use as well as the clause graph approach: as 1990 marks the fifteenth birthday of the system, the time may have come to ask: ``Was it worth the effort?''}, } @ARTICLE{OhlbachWeidenbach95, AUTHOR = {Ohlbach, Hans J{\"u}rgen and Weidenbach, Christoph}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {A Note on Assumptions about Skolem Functions}, NUMBER = {2}, PUBLISHER = {Kluwer}, VOLUME = {15}, ISBN = {0168-7433}, YEAR = {1995}, PAGES = {267--275}, ABSTRACT = {Skolemization is not an equivalence preserving transformation. For the purposes of refutational theorem proving it is sufficient that Skolemization preserves satisfiability and unsatisfiability. Therefore there is sometimes some freedom in interpreting Skolem functions in a particular way. We show that in certain cases it is possible to exploit this freedom for simplifying formulae considerably. Examples for cases where this occurs systematically are the relational translation from modal logics to predicate logic and the relativization of first-order logics with sorts.}, } @INPROCEEDINGS{P-SAS00, AUTHOR = {Podelski, Andreas}, EDITOR = {Palsberg, Jens}, TITLE = {Model Checking as Constraint Solving}, BOOKTITLE = {Proceedings of the 7th International Symposium on Static Analysis (SAS-00)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Santa Barbara, California, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1824}, ISBN = {3-540-67668-6}, YEAR = {2000}, PAGES = {221--237}, } @INPROCEEDINGS{P-VMCAI03, AUTHOR = {Podelski, Andreas}, EDITOR = {Zuck, Lenore and Attie, Paul and Cortesi, Agostino and Mukhopadhyay, Supratik}, TITLE = {Software Model Checking with Abstraction Refinement}, BOOKTITLE = {Verification, model checking, and abstract interpretation : 4th International Conference, VMCAI 2003}, PADDRESS = {Berlin, Germany}, ADDRESS = {New York, NY (USA)}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2575}, ISBN = {3-540-00348-7}, YEAR = {2003}, PAGES = {1--13}, } @INPROCEEDINGS{PacholskiPodelski97, AUTHOR = {Pacholski, Leszek and Podelski, Andreas}, EDITOR = {Smolka, Gert}, TITLE = {Set Constraints: a Pearl in Research on Constraints}, BOOKTITLE = {Proceedings of the 3rd International Conference on Principles and Practice of Constraint Programming (CP-97)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Linz, Austria}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1330}, ISBN = {3-540-63753-2}, YEAR = {1997}, PAGES = {549--562}, } @MASTERSTHESIS{Piskac2005, AUTHOR = {Piskac, Ruzica}, TITLE = {Formal Correctness of Result Checking for Priority Queues}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {February}, YEAR = {2005}, } @INPROCEEDINGS{plaisted.survey, AUTHOR = {Plaisted, David A.}, EDITOR = {Gabbay, Dov M. and Hogger, C. and Robinson, J. A. and Siekmann, J.}, TITLE = {Equational Reasoning and Term Rewriting Systems}, BOOKTITLE = {Handbook of Logic in Artificial Intelligence and Logic Programming}, PUBLISHER = {Oxford University Press}, VOLUME = {1}, YEAR = {1993}, PAGES = {273--364}, ABSTRACT = {An {\em equational system\/} is a set of equations. Often we are interested in knowing if an equation follows logically from the given set. For example, given the equations $x + y = y + x$, $(x + y) + z = x + (y + z)$, and $-(-(x+y)+ -(x+-y)) = x$, we might want to know if the equation $-(-x+y)+ -(-x+-y)=x$ is a logical consequence. As another example, we might want to know if $x * y = y * x$ in a group in which $x ^ 2 = e$ for all $x$. Such systems are of interest for computer scientists as well as mathematicians. Common data structures like lists and stacks can often be described by such sets of equations. Furthermore, systems for mechanising such proofs on a computer are becoming more and more powerful. In addition, a functional program is essentially a set of equations, typically with higher order functions, and the execution of a program is then a kind of equational reasoning. We will discuss methods of inference that are particularly adapted to equational systems without explicit higher order functions. We will also discuss systems in which the equations may have conditions attached. Next we will consider the use of equational reasoning in general theorem proving programs. We also touch on the use of equations in logic and functional programming. Our survey differs from others in several ways. In general, our survey uses formalisms based on logic, and emphasizes the relationship between syntax and semantics. Some of our notation is novel, and some results may be original. Our presentation of some topics like unfailing completion and strong sequentiality is different. We do not emphasize properties of systems with more than one rewrite relation, as do other surveys. We do not study inductive theorems; for that, see a later chapter in this series. The organization of our survey is also different than others.}, } @INPROCEEDINGS{plaisted:94b, AUTHOR = {Plaisted, David A.}, EDITOR = {Bundy, Alan}, TITLE = {The Search Efficiency of Theorem Proving Strategies}, BOOKTITLE = {Proceedings of the 12th International Conference on Automated Deduction (CADE-12)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Nancy, France}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {814}, YEAR = {1994}, PAGES = {57--71}, ABSTRACT = {We analyze the search efficiency of a number of common refutational theorem proving strategies for first-order logic. We show that most of them produce search spaces of exponential size even on simple sets of clauses, or else are not sensitive to the goal. We also discuss clause linking, a new procedure that uses a reduction to propositional calculus, and show that it, together with methods that cache subgoals, have behavior that is more favorable in some respects.}, } @INPROCEEDINGS{PnueliPodelskiRybalchenkoTACAS2005, AUTHOR = {Pnueli, Amir and Podelski, Andreas and Rybalchenko, Andrey}, EDITOR = {Halbwachs, Nicolas and Zuck, Lenore}, TITLE = {Separating Fairness and Well-Foundedness for the Analysis of Fair Discrete Systems}, BOOKTITLE = {Tools and Algorithms for the Construction and Analysis of Systems: 11th International Conference, TACAS 2005, Held as Part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2005}, PADDRESS = {Berlin, Germany}, ADDRESS = {Edinburgh, UK}, PUBLISHER = {Springer}, MONTH = {April}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3440}, ISBN = {3-540-25333}, YEAR = {2005}, PAGES = {124--139}, ABSTRACT = {Fair discrete systems (FDSs) are a computational model of concurrent programs where fairness assumptions are specified in terms of sets of states. The analysis of fair discrete systems involves a non-trivial interplay between fairness and well-foundedness (ranking functions). This interplay has been an obstacle for automation. The contribution of this paper is a new analysis of temporal properties of FDSs. The analysis uses a domain of binary relations over states labeled by sets of indices of fairness requirements. The use of labeled relations separates the reasoning on well-foundedness and fairness.}, } @INPROCEEDINGS{Podelski1998, AUTHOR = {Delzanno, Giorgio and Podelski, Andreas}, EDITOR = {Cleaveland, Rance}, TITLE = {Model Checking in {CLP}}, BOOKTITLE = {Proceedings of the 5th International Conference on Tools and Algorithms for Construction and Analysis of Systems (TACAS-99)}, ORGANIZATION = {European Association for Programming Languages and Systems (EAPLS); European Association for Theoretical Computer Science (EATCS)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Amsterdam, The Netherlands}, PUBLISHER = {Springer}, MONTH = {January}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1579}, ISBN = {3-540-65703-7}, YEAR = {1999}, PAGES = {223--239}, ABSTRACT = { We show that Constraint Logic Programming (CLP) can serve as a conceptual basis and as a practical implementation platform for the model checking of infinite-state systems. Our contributions are: (1)~a semantics-preserving translation of \emph{concurrent systems} into CLP programs, (2)~a method for verifying safety and liveness properties on the CLP programs produced by the translation. We have implemented the method in a CLP system and verified well-known examples of infinite-state programs over integers, using here linear constraints as opposed to Presburger arithmetic as in previous solutions.}, } @INPROCEEDINGS{Podelski2006d, AUTHOR = {Dr{\"a}ge, Klaus and Finkbeiner, Bernd and Podelski, Andreas}, EDITOR = {Valmari, Antti}, TITLE = {Directed Model Checking with Distance-Preserving Abstractions}, BOOKTITLE = {Model checking software : 13th International SPIN Workshop}, PADDRESS = {Berlin, Germany}, ADDRESS = {Vienna, Austria}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3925}, ISBN = {978-3-540-33102-5}, DOI = {10.1007/11691617_2 }, YEAR = {2006}, PAGES = {19--34}, ABSTRACT = {In directed model checking, the traversal of the state space is guided by an estimate of the distance from the current state to the nearest error state. This paper presents a distance-preserving abstraction for concurrent systems that allows one to compute an interesting estimate of the error distance without hitting the state explosion problem. Our experiments show a dramatic reduction both in the number of states explored by the model checker and in the total runtime. }, } @ARTICLE{Podelski2006e, AUTHOR = {Jensen, Kurt and Podelski, Andreas}, JOURNAL = {International Journal on Software Tools for Technology Transfer}, TITLE = {Tools and algorithms for the construction and analysis of systems}, NUMBER = {3}, PUBLISHER = {Springer}, VOLUME = {8}, YEAR = {2006}, PAGES = {177--179}, ABSTRACT = {This special section contains the revised and expanded versions of eight of the papers from the 10th International Conference on Tools and Algorithms for the Construction and Analysis of Systems (TACAS) held in March/April 2004 in Barcelona, Spain. The conference proceedings appeared as volume 2988 in the Lecture Notes in Computer Science series published by Springer. TACAS is a forum for researchers, developers and users interested in rigorously based tools for the construction and analysis of systems. The conference serves to bridge the gaps between different communities – including but not limited to those devoted to formal methods, software and hardware verification, static analysis, programming languages, software engineering, real-time systems, and communications protocols – that share common interests in, and techniques for, tool development. Other more theoretical papers from the conference are collected in a special section of the Theoretical Computer Science journal. }, } @PROCEEDINGS{Podelski95a, EDITOR = {Podelski, Andreas}, TITLE = {Constraint Programming: Basics and Trends}, BOOKTITLE = {Constraint Programming: Basics and Trends}, TYPE = {Selected Papers}, PADDRESS = {Berlin, Germany}, ADDRESS = {Châtillon-sur-Seine}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {910}, ISBN = {3-540-59155-9}, YEAR = {1995}, PAGES = {328}, } @INPROCEEDINGS{Podelski97, AUTHOR = {Podelski, Andreas}, EDITOR = {Maluszynski, Jan}, TITLE = {Set-Based Analysis of Logic Programs and Reactive Logic Programs}, BOOKTITLE = {Proceedings of the International Symposium on Logic Programming (ILPS-14)}, PADDRESS = {Cambridge, USA}, ADDRESS = {Leuven, Belgium}, PUBLISHER = {MIT Press}, ISBN = {0-262-63180-6}, YEAR = {1997}, PAGES = {35--36}, } @INPROCEEDINGS{PodelskiCharatonikMueller-ESOP99, AUTHOR = {Podelski, Andreas and Charatonik, Witold and M{\"u}ller, Martin}, EDITOR = {Swierstra, S. Doaitse}, TITLE = {Set-based Failure Analysis for Logic Programs and Concurrent Constraint Programs}, BOOKTITLE = {Programming Languages and Systems: Proceedings of the 8th European Symposium on Programming (ESOP-99)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Amsterdam, The Netherlands}, PUBLISHER = {Springer}, MONTH = {March}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1576}, ISBN = {3-540-65699-5}, YEAR = {1999}, PAGES = {177--192}, ABSTRACT = { This paper presents the first approximation method of the finite-failure set of a logic program by set-based analysis. In a dual view, the method yields a type analysis for programs with ongoing behaviors (perpetual processes). Our technical contributions are (1)~the semantical characterization of finite failure of logic programs over infinite trees and (2)~the design and soundness proof of the first set-based analysis of logic programs with the greatest-model semantics. Finally, we exhibit the connection between finite failure and the inevitability of the `inconsistent-store' error in fair executions of concurrent constraint programs where no process suspends forever. This indicates a potential application to error diagnosis for concurrent constraint programs}, } @PHDTHESIS{PodelskiHabil1998, AUTHOR = {Podelski, Andreas}, TITLE = {Thema der Antrittsvorlesung: Alte Resultate aus der Automatentheorie}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Habilitation thesis}, MONTH = {September}, YEAR = {1998}, } @INPROCEEDINGS{PodelskiRybalchenkoCook2006, AUTHOR = {Cook, Byron and Podelski, Andreas and Rybalchenko, Andrey}, JOURNAL = {ACM SIGPLAN Notices}, TITLE = {Termination Proofs for Systems Code}, BOOKTITLE = {PLDI 2006 : Proceedings of the ACM SIGPLAN 2006 Conference on Programming Language Design and Implementation}, PADDRESS = {New York, USA}, ADDRESS = {Ottawa, Ontario, Canada}, NUMBER = {6}, PUBLISHER = {ACM}, SERIES = {ACM SIGPLAN Notices}, VOLUME = {41}, ISBN = {1-59593-320-4}, YEAR = {2006}, PAGES = {415--426}, ABSTRACT = {Program termination is central to the process of ensuring that systems code can always react. We describe a new program termination prover that performs a path-sensitive and context-sensitive program analysis and provides capacity for large program fragments (i.e. more than 20,000 lines of code) together with support for programming language features such as arbitrarily nested loops, pointers, function-pointers, side-effects, etc.We also present experimental results on device driver dispatch routines from theWindows operating system. The most distinguishing aspect of our tool is how it shifts the balance between the two tasks of constructing and respectively checking the termination argument. Checking becomes the hard step. In this paper we show how we solve the corresponding challenge of checking with binary reachability analysis.}, } @INPROCEEDINGS{PodelskiRybalchenkoPOPL2005, AUTHOR = {Podelski, Andreas and Rybalchenko, Andrey}, EDITOR = {Palsberg, Jens and Abadi, Mart{\'i}n}, TITLE = {Transition predicate abstraction and fair termination}, BOOKTITLE = {Proceedings of the 32nd ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages, POPL 2005}, ORGANIZATION = {Association for Computing Machinery (ACM)}, PADDRESS = {New York, USA}, ADDRESS = {Long Beach, CA, USA}, PUBLISHER = {ACM}, ISBN = {1-58113-830-X}, YEAR = {2005}, PAGES = {124--139}, } @ARTICLE{PodelskiRybalchenkoTOPLAS2007, AUTHOR = {Podelski, Andreas and Rybalchenko, Andrey}, JOURNAL = {ACM Transactions on Programming Languages and Systems}, TITLE = {Transition Predicate Abstraction and Fair Termination}, ADDRESS = {New York, NY, USA}, NUMBER = {3}, PUBLISHER = {ACM}, VOLUME = {29}, DOI = {10.1145/1232420.1232422}, YEAR = {2007}, PAGES = {30}, } @TECHREPORT{PodelskiSchaeferWagner2004, AUTHOR = {Podelski, Andreas and Schaefer, Ina and Wagner, Silke}, TITLE = {Summaries for While Programs with Recursion}, INSTITUTION = {Max-Planck-Institut f{\"u}r Informatik}, TYPE = {Research Report}, ADDRESS = {Stuhlsatzenhausweg 85, 66123 Saarbr{\"u}cken, Germany}, NUMBER = {MPI-I-2004-2-007}, PUBLISHER = {AG 2 - Ganzinger}, MONTH = {December}, ISBN = {0946-011X}, YEAR = {2004}, PAGES = {22}, ABSTRACT = {Procedure summaries are an approximation of the effect of a procedure call. They have been used to prove partial correctness and safety properties. In this report, we introduce a generalized notion of procedure summaries and present a framework to verify total correctness and liveness properties of a general class of while programs with recursion. We provide a fixpoint system for computing summaries, and a proof rule for total correctness of a program given a summary. With suitable abstraction methods and algorithms for efficient summary computation, the results presented here can be used for the automatic verification of termination and liveness properties for while programs with recursion.}, } @INPROCEEDINGS{PodelskiSmolka95, AUTHOR = {Podelski, Andreas and Smolka, Gert}, EDITOR = {Sterling, Leon}, TITLE = {Operational Semantics of Constraint Logic Programming with Coroutining}, BOOKTITLE = {Proceedings of the 12th International Conference on Logic Programming}, PADDRESS = {Cambridge, USA}, ADDRESS = {Kanagawa, Japan}, PUBLISHER = {MIT Press}, YEAR = {1995}, PAGES = {449--463}, } @INPROCEEDINGS{PodelskiSmolka:CP:95, AUTHOR = {Podelski, Andreas and Smolka, Gert}, EDITOR = {Montanari, Ugo and Rossi, Francesca}, TITLE = {Situated Simplification}, BOOKTITLE = {Proceedings of the First International Conference on Principles and Practice of Constraint Programming (CP'95)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Cassis, France}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {976}, YEAR = {1995}, PAGES = {328--344}, } @TECHREPORT{PodelskiWagner01_2007, AUTHOR = {Podelski, Andreas and Wagner, Silke}, TITLE = {A Method and a Tool for Automatic Verification of Region Stability for Hybrid Systems}, INSTITUTION = {Max-Planck-Institut f{\"u}r Informatik}, TYPE = {Research Report}, ADDRESS = {Stuhlsatzenhausweg 85, 66123 Saarbr{\"u}cken, Germany}, NUMBER = {MPI-I-2007-2-001}, MONTH = {January}, YEAR = {2007}, PAGES = {46}, ABSTRACT = {We propose a model checking method and tool that integrates state abstraction techniques for the automatic proof of a stability property for hybrid systems called \emph{region stability}. It is based on a new notion of \emph{snapshots} which yield characteristic discretizations of trajectories. We have implemented the tool and applied it to solve a number of verification problems, including the fully automatic stability proof for the break curve behavior of a train system.}, } @INPROCEEDINGS{PodelskiWagner02_2007, AUTHOR = {Podelski, Andreas and Wagner, Silke}, EDITOR = {Bemporad, Alberto and Bicchi, Antonio and Buttazzo, Giorgio C.}, TITLE = {A Sound and Complete Proof Rule for Region Stability of Hybrid Systems}, BOOKTITLE = {Hybrid systems: computation and control : 10th International Conference, HSCC 2007}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, MONTH = {April}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {4416}, ISBN = {978-3-540-71492-7}, YEAR = {2007}, PAGES = {750--753}, ABSTRACT = {Region stability allows one to formalize hybrid systems whose trajectories may oscillate (within a given allowance) even after having `stabilized'. Unfortunately, until today no proof rule (giving necessary and sufficient conditions for the purpose of verifying region stability) has been available. This paper fills the gap. Our (sound and complete) proof rule connects region stability with the finiteness of specific state sequences and thus with the emerging set of verification methods for program termination.}, } @INPROCEEDINGS{PodelskiWagner03_2007, AUTHOR = {Wagner, Silke and Podelski, Andreas}, EDITOR = {Raskin, J.-F. and Thiagarajan, P.S.}, TITLE = {Region Stability Proofs for Hybrid Systems}, BOOKTITLE = {Formal Modelling and Analysis of Timed Systems: 5th International Conference, FORMATS 2007}, PADDRESS = {Berlin, Germany}, ADDRESS = {Salzburg, Austria}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {12345}, YEAR = {2007}, PAGES = {16}, ABSTRACT = {We present a method and tool (and implementation) for automatic proofs of region stability for hybrid systems. The formal basis of our approach is the new notion of \emph{snapshot sequences}. We use snapshot sequences for a characterization of region stability. Our abstraction-based algorithm checks the conditions in this characterization. A number of experiments demonstrate the practical potential of our approach.}, } @INPROCEEDINGS{PodelskiWagner2006, AUTHOR = {Podelski, Andreas and Wagner, Silke}, EDITOR = {Hespanha, João P. and Tiwari, Ashish}, TITLE = {Model Checking of Hybrid Systems: From Reachability towards Stability}, BOOKTITLE = {Hybrid Systems: Computation and Control : 9th International Workshop, HSCC 2006 }, ORGANIZATION = {ACM SIGBED}, PADDRESS = {Berlin, Germany}, ADDRESS = {Santa Barbara, CA, USA}, PUBLISHER = {Springer}, MONTH = {March}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3927}, ISBN = {978-3-540-33170-4}, YEAR = {2006}, PAGES = {507--521}, ABSTRACT = {We call a hybrid system {\em stable} if every trajectory inevitably ends up in a given region. Our notion of stability deviates from classical definitions in control theory. In this paper, we present a model checking algorithm for stability in the new sense. The idea of the algorithm is to reduce the stability proof for the whole system to a set of (smaller) proofs for several one-mode systems.}, } @INPROCEEDINGS{PodelskiWiesSAS2005, AUTHOR = {Podelski, Andreas and Wies, Thomas}, EDITOR = {Hankin, Chris and Siveroni, Igor}, TITLE = {Boolean Heaps}, BOOKTITLE = {Static analysis : 12th International Symposium, SAS 2005}, PADDRESS = {Berlin, Germany}, ADDRESS = {London, UK}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3672}, YEAR = {2005}, PAGES = {268--283}, } @INPROCEEDINGS{PR04:LinearRanking, AUTHOR = {Podelski, Andreas and Rybalchenko, Andrey}, EDITOR = {Levi, Giorgio and Steffen, Bernhard}, TITLE = {A Complete Method for the Synthesis of Linear Ranking Functions}, BOOKTITLE = {Verification, model checking, and abstract interpretation : 5th International Conference, VMCAI 2004}, ORGANIZATION = {EAPLS}, PADDRESS = {Berlin, Germany}, ADDRESS = {Venice, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2937}, ISBN = {3-540-20803-8}, YEAR = {2004}, PAGES = {239--251}, } @INPROCEEDINGS{PR04:TransInv, AUTHOR = {Podelski, Andreas and Rybalchenko, Andrey}, TITLE = {Transition Invariants}, BOOKTITLE = {Proceedings of the 19th Annual IEEE Symposium on Logic in Computer Science, LICS 2004}, ORGANIZATION = {IEEE Computer Society}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Turku, Finland}, PUBLISHER = {IEEE}, MONTH = {July}, ISBN = {0-7695-2192-4}, YEAR = {2004}, PAGES = {32--41}, } @INPROCEEDINGS{Prevosto2004, AUTHOR = {Dubois, Catherine and Jaume, Mathieu and Pons, Olivier and Prevosto, Virgile}, EDITOR = {Juilland, Jacques}, TITLE = {L'atelier FOCAL}, BOOKTITLE = {Actes du 6{\`e}me Atelier sur les Approches Formelles dans l'Assistance au D{\'e}veloppement de Logiciels (AFADL 2004)}, PADDRESS = {Besan{\c{c}}on, France}, ADDRESS = {Besan{\c{c}}on, France}, PUBLISHER = {Universit{\'e} de Franche-Comt{\'e}}, MONTH = {June}, YEAR = {2004}, PAGES = {321--324}, } @INPROCEEDINGS{PrevostoDagstuhl2005, AUTHOR = {Prevosto, Virgile}, EDITOR = {Coquand, Thierry and Lombardi, Henri and Roy, Marie-Franccoise}, TITLE = {Certified mathematical hierarchies: the {FoCal} system.}, BOOKTITLE = {Proceedings of the MAP (Mathematics, Algorithms, Proofs) Workshop}, PADDRESS = {Dagstuhl, Germany}, ADDRESS = {IBFI Schlo{\ss} Dagstuhl, Germany}, PUBLISHER = {IBFI}, SERIES = {Dagstuhl Seminar Proceedings}, VOLUME = {05021}, ISBN = {1862-4405}, YEAR = {2006}, } @INPROCEEDINGS{PrevostoTLCA2005, AUTHOR = {Prevosto, Virgile and Boulm{\'e}, Sylvain}, EDITOR = {Urzyczyn, Pawe{ł}}, TITLE = {Proof Contexts with Late Binding}, BOOKTITLE = {Typed Lambda Calculi and Applications: 7th International Conference, TLCA 2005}, PADDRESS = {Berlin, Germany}, ADDRESS = {Nara, Japan}, PUBLISHER = {Springer}, MONTH = {April}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3461}, ISBN = {3-540-25593-1}, YEAR = {2005}, PAGES = {325--339}, NOTE = {To appear}, ABSTRACT = {The focal language (formerly Foc) allows one to incrementally build modules and to prove formally their correctness. focal encourages a development process by refinement, deriving step-by-step implementations from specifications. This refinement process is realized using an inheritance mechanism on structures which can mix primitive operations, axioms, algorithms and proofs. Inheriting from existing structures allows to reuse their components under some conditions, statically checked by the compiler. This paper presents two formal semantics for encoding focal constructions in the Coq proof assistant. The first one is a shallow embedding which gives a practical way to use Coq to check proofs in focal libraries. The second one formalizes the focal structures as Coq types (called mixDrecs) and shows that the informal semantics of focal libraries is coherent with respect to Coq logic. In the last part of the paper, we prove that the first embedding is conform to the mixDrecs model.}, } @INPROCEEDINGS{PrevostoWaldmann2006, AUTHOR = {Prevosto, Virgile and Waldmann, Uwe}, EDITOR = {Sutcliffe, Geoff and Schmidt, Renate and Schulz, Stephan}, TITLE = {{SPASS+T}}, BOOKTITLE = {ESCoR: FLoC'06 Workshop on Empirically Successful Computerized Reasoning}, PADDRESS = {-}, ADDRESS = {Seattle, WA, USA}, PUBLISHER = {-}, SERIES = {CEUR Workshop Proceedings}, VOLUME = {192}, ISBN = {1613-0073}, YEAR = {2006}, PAGES = {18--33}, ABSTRACT = {SPASS+T is an extension of the superposition-based theorem prover SPASS that allows us to enlarge the reasoning capabilities of SPASS using an arbitrary SMT procedure for arithmetic and free function symbols as a black-box. We discuss the architecture of SPASS+T and the capabilities, limitations, and applications of such a combination.}, } @INPROCEEDINGS{PSW:05, AUTHOR = {Podelski, Andreas and Schaefer, Ina and Wagner, Silke}, EDITOR = {Sagiv, Mooly}, TITLE = {Summaries for While Programs with Recursion}, BOOKTITLE = {Programming Languages and Systems: 14th European Symposium on Programming, ESOP 2005, Held as Part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2005}, PADDRESS = {Berlin, Germany}, ADDRESS = {Edinburgh, UK}, PUBLISHER = {Springer}, MONTH = {April}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3444}, ISBN = {3-540-25435-8}, YEAR = {2005}, PAGES = {94--107}, ABSTRACT = {Procedure summaries are an approximation of the effect of a procedure call. They have been used to prove partial correctness and safety properties. In this paper, we introduce a generalized notion of procedure summaries and present a framework to verify total correctness and liveness properties of a general class of while programs with recursion. We provide a fixpoint system for computing summaries, and a proof rule for total correctness of a program given a summary. With suitable abstraction methods and algorithms for efficient summary computation, the results presented here can be used for the automatic verification of termination and liveness properties for while programs with recursion.}, } @ARTICLE{r-cppipd-00, AUTHOR = {Krishna Rao, M. R. K.}, JOURNAL = {Theoretical Computer Science}, TITLE = {Some classes of prolog programs inferable from positive data}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {1/2}, PUBLISHER = {Elsevier}, VOLUME = {241}, ISBN = {0304-3975}, YEAR = {2000}, PAGES = {211--223}, NOTE = {Special issue for ALT '96}, } @ARTICLE{Rao:2000:SCS, AUTHOR = {Krishna Rao, M. R. K.}, JOURNAL = {Theoretical Computer Science}, TITLE = {Some characteristics of strong innermost normalization}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {1}, PUBLISHER = {Elsevier}, VOLUME = {239}, ISBN = {0304-3975}, YEAR = {2000}, PAGES = {141--164}, } @INPROCEEDINGS{Ratschan2002, AUTHOR = {Ratschan, Stefan and Vehi, Josep}, EDITOR = {Bittanti, Sergio}, TITLE = {Robust Pole Clustering of Parametric Uncertain Systems Using Interval Methods}, BOOKTITLE = {Robust control design 2003 : (ROCOND 2003) ; a proceedings volume from the 4th IFAC symposium}, ORGANIZATION = {IFAC}, PADDRESS = {Oxford}, ADDRESS = {Milano}, PUBLISHER = {Publ. for the International Federation of Automatic Control by Elsevier}, ISBN = {0-08-044012-6}, YEAR = {2004}, PAGES = {323--328}, ABSTRACT = { In this paper a new methodology to solve the pole clustering problem for parametric uncertain systems is introduced: The problem of clustering the closed loop poles into prescribed D-regions in the complex plane is stated as a quantified constraint problem that represents bounded uncertain parameters by intervals; and an engineering-oriented approach based on interval methods is developed to solve this quantified constraint problem. The result is a new, robust, reliable and design oriented method to deal with parametric uncertain systems. The methodology presented in this paper allows to find a good controller that places the closed loop poles in the desired location in the complex plane. In case there is no solution, the method allows also to "tune" the problem, either enlarging the pole locations or reducing the uncertainty domain. The approach presented in this paper can be used either for linear or non-linear systems and for any kind of parametric bounded uncertainty. Several simple examples illustrate the uses, limits and scope of the methodology.}, } @INPROCEEDINGS{Ratschan2003, AUTHOR = {Ratschan, Stefan}, EDITOR = {Rossi, Francesca}, TITLE = {Solving Existentially Quantified Constraints with One Equality and Arbitrarily Many Inequalities}, BOOKTITLE = {Principles and practice on constraint programming - CP 2003 : 9th International Conference, CP 2003}, PADDRESS = {Berlin, Germany}, ADDRESS = {Kinsale, Ireland}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {2833}, YEAR = {2003}, PAGES = {615--633}, ABSTRACT = { This paper contains the first algorithm that can solve disjunctions of constraints of the form $\exists\SVec{y}\STI B \; [ f=0 \;\wedge\; g_1\geq 0\wedge\dots\wedge g_k\geq 0 ]$ in free variables $\SVec{x}$, terminating for all cases when this results in a numerically well-posed problem. Here the only assumption on the terms $f, g_1,\dots, g_n$ is the existence of a pruning function, as given by the usual constraint propagation algorithms or by interval evaluation. The paper discusses the application of an implementation of the resulting algorithm on problems from control engineering, parameter estimation, and computational geometry.}, } @ARTICLE{Ratschan2004a, AUTHOR = {Jaulin, Luc and Ratschan, Stefan and Hardouin, Laurent}, JOURNAL = {Reliable Computing}, TITLE = {Set Computation for Nonlinear Control}, NUMBER = {1}, PUBLISHER = {Kluwer}, VOLUME = {10}, YEAR = {2004}, PAGES = {1--26}, } @ARTICLE{Ratschan2004b, AUTHOR = {Ratschan, Stefan}, JOURNAL = {ACM Transactions on Computational Logic}, TITLE = {Convergent Approximate Solving of First-order Constraints by Approximate Quantifiers}, NUMBER = {2}, PUBLISHER = {ACM}, VOLUME = {5}, YEAR = {2004}, PAGES = {264--281}, } @INPROCEEDINGS{Ratschan2005, AUTHOR = {Ratschan, Stefan and She, Zhikun}, EDITOR = {Morari, Manfred and Thiele, Lothar}, TITLE = {Safety Verification of Hybrid Systems by Constraint Propagation Based Abstraction Refinement}, BOOKTITLE = {Hybrid Systems: Computation and Control: 8th International Workshop, HSCC 2005}, PADDRESS = {Berlin, Germany}, ADDRESS = {Z{\"u}rich, Schweiz}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3414}, ISBN = {3-540-25108-1}, YEAR = {2005}, PAGES = {573--589}, ABSTRACT = { This paper deals with the problem of safety verification of non-linear hybrid systems. We start from a classical method that uses interval arithmetic to check whether trajectories can move over the boundaries in a rectangular grid. We put this method into an abstraction refinement framework and improve it by developing an additional refinement step that employs constraint propagation to add information to the abstraction without introducing new grid elements. Moreover, the resulting method allows switching conditions, initial states and unsafe states to be described by complex constraints instead of sets that correspond to grid elements. Nevertheless, the method can be easily implemented since it is based on a well-defined set of constraints, on which one can run any constraint propagation based solver. First tests of such an implementation are promising.}, } @ARTICLE{Ratschan2005a, AUTHOR = {Ratschan, Stefan}, JOURNAL = {ACM Transactions on Computational Logic}, TITLE = {Efficient Solving of Quantified Inequality Constraints over the Real Numbers}, NUMBER = {4}, PUBLISHER = {ACM}, VOLUME = {7}, YEAR = {2006}, PAGES = {723--748}, ABSTRACT = {Let a quantified inequality constraint over the reals be a formula in the first-order predicate language over the structure of the real numbers, where the allowed predicate symbols are $\leq$ and $<$. Solving such constraints is an undecidable problem when allowing function symbols such $\sin$ or $\cos$. In the paper we give an algorithm that terminates with a solution for all, except for very special, pathological inputs. We ensure the practical efficiency of this algorithm by employing constraint programming techniques.}, } @INPROCEEDINGS{Ratschan2005b, AUTHOR = {Ratschan, Stefan}, EDITOR = {Dolzmann, Andreas and Seidl, Andreas and Sturm, Thomas}, TITLE = {Solving Undecidable Problems in the Theory of Real Numbers and Hybrid Systems}, BOOKTITLE = {Algorithmic Algebra and Logic; Conference in Honor of the 60th Birthday of Volker Weispfenning}, PADDRESS = {Norderstedt, Germany}, ADDRESS = {Passau, Germany}, PUBLISHER = {Books on Demand GmbH}, ISBN = {3-8334-2669-1}, YEAR = {2005}, PAGES = {213--216}, } @INPROCEEDINGS{Ratschan2006, AUTHOR = {Ratschan, Stefan and Smaus, Jan-Georg}, EDITOR = {Cassandras, Christos and Giua, Alessandro and Seatzu, Carla and Zaytoon, Janan}, TITLE = {Verification-Integrated Falsification of Non-Deterministic Hybrid Systems}, BOOKTITLE = {2nd IFAC Conference on Analysis and Design of Hybrid Systems}, PADDRESS = {Oxford, UK}, ADDRESS = {Alghero, Italy}, PUBLISHER = {Elsevier}, MONTH = {November}, SERIES = {IFAC Proceedings Volumes}, ISBN = {0080446132}, YEAR = {2006}, } @ARTICLE{Ratschan2007, AUTHOR = {Ratschan, Stefan and She, Zhikun}, JOURNAL = {ACM Transactions in Embedded Computing Systems}, TITLE = {Safety Verification of Hybrid Systems by Constraint Propagation Based Abstraction Refinement}, ADDRESS = {New York, NY, USA}, NUMBER = {1}, PUBLISHER = {ACM}, VOLUME = {6}, ISBN = {1539-9087}, DOI = {10.1145/1210268.1210276}, YEAR = {2007}, PAGES = {1--23}, ABSTRACT = {This paper deals with the problem of safety verification of nonlinear hybrid systems. We start from a classical method that uses interval arithmetic to check whether trajectories can move over the boundaries in a rectangular grid. We put this method into an abstraction refinement framework and improve it by developing an additional refinement step that employs interval-constraint propagation to add information to the abstraction without introducing new grid elements. Moreover, the resulting method allows switching conditions, initial states, and unsafe states to be described by complex constraints, instead of sets that correspond to grid elements. Nevertheless, the method can be easily implemented, since it is based on a well-defined set of constraints, on which one can run any constraint propagation-based solver. Tests of such an implementation are promising. }, } @MASTERSTHESIS{RauRainer97, AUTHOR = {Rau, Rainer}, TITLE = {Adaption of a Fuzzy Controller for a Cybernetic System through an Evolutionary Algorithm}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1997}, NOTE = {Rainer Rau obtained his Diploma in Computer Science from Saarland University in 1997. The supervisor of the work was Hans J{\"u}rgen Ohlbach}, } @MASTERSTHESIS{ReinoldDipl91, AUTHOR = {Reinold, Michael}, TITLE = {{Transformation in dichten W{\"a}ldern}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1991}, } @INPROCEEDINGS{rel-ripp-ijcai, AUTHOR = {Bundy, Alan and Lombart, V.}, EDITOR = {Mellish, C.}, TITLE = {Relational Rippling: a General Approach}, BOOKTITLE = {Proceedings of the Fourteenth International Joint Conference on Artificial Intelligence (IJCAI-95)}, ORGANIZATION = {IJCAI}, PADDRESS = {San Francisco, USA}, ADDRESS = {Montr{\'e}al, Canada}, PUBLISHER = {Morgan Kaufmann}, ISBN = {1-55860-363-8}, YEAR = {1995}, PAGES = {175--181}, } @MASTERSTHESIS{Rock95, AUTHOR = {Rock, Georg}, TITLE = {Transformations of First-Order Formulae for Automated Reasoning}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {July}, YEAR = {1995}, ABSTRACT = {Theorem prover for first-order logic usually operate on a set of clauses. Since it is more natural and adequate to code problems in full first-order logic, the problem of translating a formula into clause normal form is an important one in this field. From experience we know that a theorem prover can find a proof more easily with a compact clause normal form than with a huge set of clauses. In this thesis we present powerful methods to obtain compact clause normal forms.}, } @ARTICLE{Romina2004, AUTHOR = {Goncharov, Sergey and Harizanov, Valentina and Knight, Julia F. and Morozov, Andrey and Romina, Anya}, JOURNAL = {Siberian Mathematical Journal}, TITLE = {On automorphic tuples of elements in computable models}, ADDRESS = {New York LLC}, NUMBER = {3}, PUBLISHER = {Consultants Bureau, An Imprint of Springer}, VOLUME = {46}, ISBN = {0037-4466}, YEAR = {2005}, PAGES = {405--412}, } @TECHREPORT{rp780, AUTHOR = {Frank, Ian and Basin, David A.}, TITLE = {Search in Games with Incomplete Information: A Case Study Using Bridge Card Play}, INSTITUTION = {Department of Artificial Intelligence}, TYPE = {Research Paper}, ADDRESS = {Edinburgh, UK}, NUMBER = {780}, YEAR = {1996}, PAGES = {28}, NOTE = {Also Available as journal article (Artificial Intelligence)}, ABSTRACT = {We examine search algorithms in games with incomplete information, formalising a best defence model of such games based on the assumptions typically made when incomplete information problems are analysed in expert texts. We show that equilibrium point strategies for optimal play exist for this model, and define an algorithm capable of computing such strategies. Using this algorithm as a reference we then analyse search architectures that have been proposed for the incomplete information game of Bridge. These architectures select strategies by analysing some statistically significant collection of complete information sub-games. Our model allows us to clearly state the limitations of such architectures in producing expert analysis, and to precisely formalise and distinguish the problems that lead to sub-optimality. We illustrate these problems with simple game trees and with actual play situations from Bridge itself.}, } @INPROCEEDINGS{Rybalchenko-Sofronie-vmcai07, AUTHOR = {Rybalchenko, Andrey and Sofronie-Stokkermans, Viorica}, EDITOR = {Cook, Byron and Podelski, Andreas}, TITLE = {Constraint Solving for Interpolation}, BOOKTITLE = {8th International Conference on Verification, Model Checking and Abstract Interpretation (VMCAI 2007)}, PADDRESS = {-}, ADDRESS = {Nice, France}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, YEAR = {2007}, ABSTRACT = {Interpolation is an important component of recent methods for program verification. It provides a natural and effective means for computing separation between the sets of `good' and `bad' states. The existing algorithms for interpolant generation are proof-based: They require explicit construction of proofs, from which interpolants can be computed. Construction of such proofs is a difficult task. We propose an algorithm for the generation of interpolants for the combined theory of linear arithmetic and uninterpreted function symbols that does not require a priori constructed proofs to derive interpolants. It uses a reduction of the problem to constraint solving in linear arithmetic, which allows application of existing highly optimized Linear Programming solvers in black-box fashion. We provide experimental evidence of the practical applicability of our algorithm.}, } @MASTERSTHESIS{Rybalchenko2002, AUTHOR = {Rybalchenko, Andrey}, TITLE = {A Model Checker based on Abstraction Refinement}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, ADDRESS = {Saarbr{\"u}cken, Saarland}, MONTH = {September}, YEAR = {2002}, NOTE = {1.0}, ABSTRACT = {Abstraction plays an important role for verification of computer programs. We want to construct the right abstraction automatically. There is a promising approach to do it, called {\it predicate abstraction}. An insufficiently precise abstraction can be {\it automatically refined}. There is an automated model checking method described in [Ball, Podelski, Rajamani TACAS02] which combines both techniques, e.g., predicate abstraction and abstraction refinement. The quality of the method is expressed by a completeness property relative to a powerful but unrealistic oracle-guided algorithm. \par In this work we want to generalize the results from [Ball,Podelski,Rajamani TACAS02] and introduce new abstraction functions with different precision. We implement the new abstraction functions in a model checker and practically evaluate their effectiveness in verifying various computer programs. }, } @INPROCEEDINGS{Rybalchenko2006ICTAC-DC, AUTHOR = {Meyer, Roland and Faber, Johannes and Rybalchenko, Andrey}, EDITOR = {Barkaoui, Kamel and Cavalcanti, Ana and Cerone, Antonio}, TITLE = {Model checking Duration Calculus: a practical approach}, BOOKTITLE = {Theoretical Aspects of Computing - ICTAC 2006 : Third International Colloquium}, ORGANIZATION = {ICTAC}, PADDRESS = {Berlin, Germany}, ADDRESS = {Tunis, Tunisia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {4281}, ISBN = {3-540-48815-4}, DOI = {10.1007/11921240_23}, YEAR = {2006}, PAGES = {332--346}, ABSTRACT = {Model checking of real-time systems with respect to Duration Calculus (DC) specifications requires the translation of DC formulae into automata-based semantics. This task is difficult to automate. The existing algorithms provide a limited DC coverage and do not support compositional verification. We propose a translation algorithm that advances the applicability of model checking tools to real world applications. Our algorithm significantly extends the subset of DC that can be handled. It decomposes DC specifications into sub-properties that can be verified independently. The decomposition bases on a novel distributive law for DC. We implemented the algorithm as part of our tool chain for the automated verification of systems comprising data, communication, and real-time aspects. Our translation facilitated a successful application of the tool chain on an industrial case study from the European Train Control System (ETCS). }, } @INPROCEEDINGS{Rybalchenko2007PADL, AUTHOR = {Podelski, Andreas and Rybalchenko, Andrey}, EDITOR = {Hanus, Michael}, TITLE = {ARMC: The Logical Choice for Software Model Checking with Abstraction Refinement}, BOOKTITLE = {Practical aspects of declarative languages : 9th International Symposium, PADL 2007}, PADDRESS = {Berlin, Germany}, ADDRESS = {Nice, France}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {4354}, ISBN = {978-3-540-69608-7}, DOI = {10.1007/978-3-540-69611-7_16}, YEAR = {2007}, PAGES = {245--259}, ABSTRACT = {Software model checking with abstraction refinement is emerging as a practical approach to verify industrial software systems. Its distinguishing characteristics lie in the way it applies logical reasoning to deal with abstraction. It is therefore natural to investigate whether and how the use of a constraint-based programming language may lead to an elegant and concise implementation of a practical tool. In this paper we describe the outcome of our investigation. Using a Prolog system together with Constraint Logic Programming extensions as the implementation platform of our choice we have built such a tool, called ARMC (for Abstraction Refinement Model Checking), which has already been used for practical verification. }, } @INPROCEEDINGS{Rybalchenko2007PLDI-Paths, AUTHOR = {Beyer, Dirk and Henzinger, Thomas and Majumdar, Rupak and Rybalchenko, Andrey}, EDITOR = {Ferrante, Jeanne and McKinley, Kathryn S.}, TITLE = {Path Invariants}, BOOKTITLE = {PLDI'07 : Proceedings of the ACM SIGPLAN 2007 Conference on Programming Language Design and Implementation}, PADDRESS = {New York, NY, USA}, ADDRESS = {San Diego, CA, USA}, PUBLISHER = {ACM}, ISBN = {978-1-59593-633-2}, DOI = {10.1145/1250734.1250769}, YEAR = {2007}, PAGES = {300--309}, ABSTRACT = {The success of software verification depends on the ability to find a suitable abstraction of a program automatically. We propose a method for automated abstraction refinement which overcomes some limitations of current predicate discovery schemes. In current schemes, the cause of a false alarm is identified as an infeasible error path, and the abstraction is refined in order to remove that path. By contrast, we view the cause of a false alarm -the spurious counterexample- as a full-fledged program, namely, a fragment of the original program whose control-flow graph may contain loops and represent unbounded computations. There are two advantages to using such path programs as counterexamples for abstraction refinement. First, we can bring the whole machinery of program analysis to bear on path programs, which are typically small compared to the original program. Specifically, we use constraint-based invariant generation to automatically infer invariants of path programs-so-called path invariants. Second, we use path invariants for abstraction refinement in order to remove not one infeasibility at a time, but at once all (possibly infinitely many) infeasible error computations that are represented by a path program. Unlike previous predicate discovery schemes, our method handles loops without unrolling them; it infers abstractions that involve universal quantification and naturally incorporates disjunctive reasoning.}, } @INPROCEEDINGS{Rybalchenko2007PLDI-Threads, AUTHOR = {Cook, Byron and Podelski, Andreas and Rybalchenko, Andrey}, EDITOR = {Ferrante, Jeanne and McKinley, Kathryn S.}, TITLE = {Proving Thread Termination}, BOOKTITLE = {PLDI'07 : Proceedings of the ACM SIGPLAN 2007 Conference on Programming Language Design and Implementation}, PADDRESS = {New York, NY, USA}, ADDRESS = {San Diego, CA, USA}, PUBLISHER = {ACM}, ISBN = {978-1-59593-633-2}, DOI = {10.1145/1250734.1250771}, YEAR = {2007}, PAGES = {320--330}, ABSTRACT = {Concurrent programs are often designed such that certain functions executing within critical threads must terminate. Examples of such cases can be found in operating systems, web servers, e-mail clients, etc. Unfortunately, no known automatic program termination prover supports a practical method of proving the termination of threads. In this paper we describe such a procedure. The procedure's scalability is achieved through the use of environment models that abstract away the surrounding threads. The procedure's accuracy is due to a novel method of incrementally constructing environment abstractions. Our method finds the conditions that a thread requires of its environment in order to establish termination by looking at the conditions necessary to prove that certain paths through the thread represent well-founded relations if executed in isolation of the other threads. The paper gives a description of experimental results using an implementation of our procedureon Windows device drivers and adescription of a previously unknown bug found withthe tool.}, } @INPROCEEDINGS{Rybalchenko2007POPL, AUTHOR = {Cook, Byron and Gotsman, Alexey and Podelski, Andreas and Rybalchenko, Andrey and Vardi, Moshe}, EDITOR = {Hofmann, Martin and Felleisen, Matthias}, TITLE = {Proving that programs eventually do something good}, BOOKTITLE = {34th ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages (POPL 2007)}, PADDRESS = {New York, USA}, ADDRESS = {Nice, France}, PUBLISHER = {ACM}, ISBN = {1-59593-575-4}, YEAR = {2007}, PAGES = {265--276}, } @INPROCEEDINGS{Rybalchenko2007VMCAI-InvGen, AUTHOR = {Beyer, Dirk and Henzinger, Thomas and Majumdar, Rupak and Rybalchenko, Andrey}, EDITOR = {Cook, Byron and Podelski, Andreas}, TITLE = {Invariant Synthesis for Combined Theories}, BOOKTITLE = {Verification, Model Checking, and Abstract Interpretation : 8th International Conference, VMCAI 2007}, PADDRESS = {Berlin, Germany}, ADDRESS = {Nice, France}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {4349}, ISBN = {978-3-540-69735-0}, YEAR = {2007}, PAGES = {378--394}, } @MASTERSTHESIS{Schaef2005, AUTHOR = {Sch{\"a}f, Martin}, TITLE = {{Abstrakte {\"U}bergangsrelationen als Mittel zur Verifikation von Programmeigenschaften}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {April}, YEAR = {2006}, ABSTRACT = {Die Entwicklung von Software ist ein fehleranf¨alliger Prozess. Allein die Tatsache, dass ein Programm ausf¨uhrbar ist und dass f¨ur eine begrenzte Menge von Testf¨allen keine Fehler in der Ausf¨uhrung des Programms auftritt, sagt nicht aus, dass ein Programm fehlerfrei ist. Vor allem in Bereichen, in denen Software nicht einfach im Fall eines Versagens abgeschaltet und repariert werden kann ist es wichtig beweisen zu k¨onnen, dass Software fehlerfrei ist. Es existieren verschiedene Methoden diesen Beweis zu erbringen. Die g¨angigste Methode ist deduktive Verifikation, in der die Software von Hand verifiziert wird. Dieser Vorgang ist allerdings teuer und fehleranf¨allig. Formale Verifikation ist eine j¨ungere Methode die vor allem f¨ur die Verifikation von Hardware verwendet wird. Mit formaler Verifikation k¨onnen Systeme mit endlicher Zustandsmenge automatisch bewiesen werden. Um die Methode auf Software anzuwenden, muss diese abstrahiert werden, da die Zustandsmenge eines Programms unendlich gross sein kann. Das U¨ berpr ¨ufen von Programmeigenschaften auf einem abstrakten Modell wird auch Model Checking genannt. Es existieren verschiedene Ans¨atze um durch Model Checking Programmeigenschaften zu beweisen. In [esp] wird ein Ansatz vorgestellt tempor¨are Sicherheitseigenschaften eines Programms automatisch zu Beweisen. [tin] stellt eine M¨oglichkeit vor durch Model Checking Terminierung und Fairness zu beweisen. Diese Ans¨atze arbeiten immer auf dem gesamten Programm. In dieser Arbeit wird eine Methode hergeleitet, ein Programm oder einen Teil eines Programms in eine abstrakte U¨ bergangsrelation zu u¨bersetzen und durch diese, Annahmen ¨uber das Verhalten der Programmvariablen zu beweisen. Der Vorteil dieser Methode ist die Wiederverwendbarkeit von U¨ bergangsrelationen. Da diese unabh¨angig vom Kontrollfluss sind, gen¨ugt es, f¨ur einen Programmteil einmalig die U¨ bergangsrelation zu berechnen, egal wie oft dieser Teil verwendet wird. Diese Eigenschaft bietet es an, dieses Verfahren in den Prozess der Softwareentwicklung einzubeziehen um die Fehlersuche zu erleichtern, oder Fehler fr¨uhzeitig zu erkennen. 4}, } @MASTERSTHESIS{Schlobach97, AUTHOR = {Schlobach, Stefan}, TITLE = {Untersuchung nicht-monotoner Logiken - Fallstudie zur Automatisierung}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {1996}, } @INPROCEEDINGS{Schmidt92a, AUTHOR = {Schmidt, Renate A.}, EDITOR = {Ohlbach, Hans J{\"u}rgen}, TITLE = {Terminological Representation, Natural Language \& Relation Algebra}, BOOKTITLE = {GWAI-92: Advances in Artificial Intelligence: Proc.~16th German Workshop on Artificial Intelligence}, PADDRESS = {Berlin, Germany}, ADDRESS = {Bonn, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {671}, YEAR = {1993}, PAGES = {357--371}, NOTE = {Also available as Research Report MPI-I-92-246}, ABSTRACT = {In this paper I establish a link between {\sc kl-one}-based knowledge representation concerned with {\em terminological representation} and the work of P. Suppes (1976,1979,1981) and M. B\"ottner (1985,1989) in computational linguistics. I show how this link can be utilised for the problem of finding adequate terminological representations for given information formulated in ordinary English.}, } @INPROCEEDINGS{Schmidt94, AUTHOR = {Schmidt, Renate A.}, EDITOR = {Brink, C. and Schmidt, G.}, TITLE = {Peirce Algebras and Their Applications in Artificial Intelligence and Computational Linguistics: Abstract}, BOOKTITLE = {Relational Methods in Computer Science; Dagstuhl Seminar Report 80 (9403)}, PADDRESS = {Wadern, Germany}, ADDRESS = {Schlo{\ss} Wadern}, PUBLISHER = {IBFI}, YEAR = {1994}, PAGES = {21--22}, } @ARTICLE{Schmidt94a, AUTHOR = {Schmidt, Renate A.}, JOURNAL = {SIGALA Newsletter}, TITLE = {Peirce Algebras and Their Applications in Artificial Intelligence and Computational Linguistics: Abstract}, NUMBER = {1}, MONTH = {April}, VOLUME = {2}, YEAR = {1994}, PAGES = {27--27}, NOTE = {Abstract of a talk held at the Dagstuhl Seminar on Relational Methods in Computer Science, Dagstuhl, Germany (January 1994). Also in Brink, C. and Schmidt, G. (eds) (1994), Relational Methods in Computer Science, Dagstuhl-Seminar-Report 80 (9403), IBFI, Schlo{\ss} Dagstuhl, Wadern, Germany.}, } @INPROCEEDINGS{Schmidt94b, AUTHOR = {Schmidt, Renate A.}, EDITOR = {Kunze, J{\"u}rgen and Stoyan, Herbert}, TITLE = {Terminological Logics and Conceptual Graphs: An Historical Perspective}, BOOKTITLE = {KI-94 Workshops: Extended Abstracts}, PADDRESS = {Bonn, Germany}, ADDRESS = {Saarbr{\"u}cken, Germany}, PUBLISHER = {Gesellschaft f{\"u}r Informatik}, MONTH = {September}, YEAR = {1994}, PAGES = {135--136}, } @INCOLLECTION{Schmidt97a, AUTHOR = {Schmidt, Renate A.}, EDITOR = {B{\"o}ttner, Michael and Th{\"u}mmel, W.}, TITLE = {Relational Grammars for Knowledge Representation}, BOOKTITLE = {Variable-Free Semantics}, ORGANIZATION = {Fachbereich Sprach- und Literaturwissenschaft, Univ. Osnabr{\"u}ck}, ADDRESS = {Osnabr{\"u}ck, Germany}, PUBLISHER = {secolo Verlag}, SERIES = {Artikulation und Sprache}, YEAR = {2000}, PAGES = {162--180}, ABSTRACT = {This paper aims to enhance the practical applicability of relational grammars, which have been devised for the semantic analysis of natural language. We focus on their application in knowledge representation. In particular, we address how the representation problem for \textsc{kl-one}-based knowledge epresentation systems can be automatically solved with the help of relational grammars. New rules are presented for natural language formulations, like \textit{has sons} and \textit{has at least two sons}, commonly arising in application domains. To this end Peirce algebras are extended with numerical quantifier operations.}, } @PHDTHESIS{Schmidt97d, AUTHOR = {Schmidt, Renate A.}, TITLE = {Optimised Modal Translation and Resolution}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {November}, YEAR = {1997}, ABSTRACT = {This thesis studies the optimised functional translation of propositional modal logics to first-order logic, and first-order resolution as a means for realising modal reasoning. The optimised functional translation maps modal logics to a lattice of clausal logics, called path logics. The general apparatus of inference for path logics is theory resolution. We show that satisfiability in basic path logic and certain extensions can be decided by resolution and condensing without requiring additional refinement strategies. We propose an improved theory unification algorithm for \textit{S4}, and we present a calculus of ordered $E$-resolution with normalisation. We show also that some essentially second-order modal logics convert to path logics, which can be exploited for accomodating inference for modal logics with numerical quantifiers in a calculus of resolution and simple arithmetic.}, } @INPROCEEDINGS{Schmidt98c, AUTHOR = {Schmidt, Renate A.}, EDITOR = {Nipkow, Tobias}, TITLE = {E-Unification for Subsystems of S4}, BOOKTITLE = {Proceedings of the 9th International Conference on Rewriting Techniques and Applications (RTA-98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Tsukuba, Japan}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1379}, ISBN = {3-540-64301-X}, YEAR = {1998}, PAGES = {106--120}, ABSTRACT = {This paper is concerned with the unification problem in the path logics associated by the optimised functional translation method with the modal logics \textit{K}, \textit{KD}, \textit{KT}, \textit{KD4}, \textitl{S4} and \textit{S5}. It presents improved unification algorithms for certain forms of the right identity and associativity laws. The algorithms employ mutation rules, which have the advantage that terms are worked off from the outside inward, making paramodulating into terms superfluous.}, } @INCOLLECTION{Schmidt98f, AUTHOR = {Schmidt, Renate A.}, EDITOR = {Kracht, M. and de Rijke, M. and Wansing, H. and Zakharyaschev, M.}, TITLE = {Resolution is a Decision Procedure for Many Propositional Modal Logics}, BOOKTITLE = {Advances in Modal Logic, Volume 1}, CHAPTER = {13}, ADDRESS = {Stanford, USA}, PUBLISHER = {CSLI}, MONTH = {April}, SERIES = {CSLI Lecture Notes}, VOLUME = {87}, ISBN = {1-57586-103-8 (hardback)}, YEAR = {1998}, PAGES = {189--208}, ABSTRACT = {The paper shows satisfiability in many propositional modal systems, including \textit{K}, \textit{KD}, \textit{KT} and \textit{KB}, their combinations as well as their multi-modal versions, can be decided by ordinary resolution procedures. This follows from a general result that resolution and condensing is a decision procedure for the satisfiability problem of formulae in so-called \emph{path logics}. Path logics arise from propositional and normal uni- and multi-modal logics by the \emph{optimised functional translation} method. The decision result provides an alternative decision proof for the relevant modal systems, and related systems in artificial intelligence. However, this alone is not very interesting. A more far-reaching consequence of the result has practical value, namely, any standard first-order theorem prover that is based on resolution can serve as a reasonable and efficient inference tool for modal reasoning.}, } @ARTICLE{Schmidt99a, AUTHOR = {Schmidt, Renate A.}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {Decidability by Resolution for Propositional Modal Logics}, NUMBER = {4}, PUBLISHER = {Kluwer}, MONTH = {May}, VOLUME = {22}, YEAR = {1999}, PAGES = {379--396}, ABSTRACT = {The paper shows that satisfiability in a range of popular propositional modal systems can be decided by ordinary resolution procedures. This follows from a general result that resolution combined with condensing, and possibly some additional form of normalisation, is a decision procedure for the satisfiability problem in certain so-called path logics. Path logics arise from normal propositional modal logics by the optimised functional translation method. The decision result provides an alternative method of proving decidability for modal logics, as well as closely related systems of artificial intelligence. This alone is not interesting. A more far-reaching consequence of the result has practical value, namely, any fair implementation of a first-order theorem prover which is based on resolution is suitable for facilitating modal reasoning.}, } @INPROCEEDINGS{SchmidtHustadt03b, AUTHOR = {Schmidt, Renate A. and Hustadt, Ullrich}, EDITOR = {Baader, Franz}, TITLE = {A Principle for Incorporating Axioms into the First-Order Translation of Modal Formulae}, BOOKTITLE = {Automated deduction, CADE-19 : 19th International Conference on Automated Deduction}, PADDRESS = {Berlin, Germany}, ADDRESS = {Miami, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2741}, ISBN = {3-540-40559-3}, YEAR = {2003}, PAGES = {412--426}, ABSTRACT = {In this paper we present a translation principle, called the \emph{axiomatic translation}, for reducing propositional modal logics with background theories, including triangular properties such as transitivity, Euclideanness and functionality, to decidable logics. The goal of the axiomatic translation principle is to find simplified theories, which capture the inference problems in the original theory, but in a way that is more amenable to automation and easier to deal with by existing theorem provers. The principle of the axiomatic translation is conceptually very simple and can be largely automated. Soundness is automatic under reasonable assumptions, and termination of ordered resolution is easily achieved, but the non-trivial part of the approach is proving completeness.}, } @INPROCEEDINGS{SchmidtOrlowskaHustadt04a, AUTHOR = {Schmidt, Renate A. and Orłowska, Ewa and Hustadt, Ullrich}, EDITOR = {Berghammer, Rudolf and M{\"o}ller, Bernhard and Struth, Georg}, TITLE = {Two Proof Systems for {Peirce} Algebras}, BOOKTITLE = {Relational and Kleene-Algebraic Methods in Computer Science: 7th International Seminar on Relational Methods in Computer Science and 2nd International Workshop on Applications of Kleene Algebra}, PADDRESS = {Berlin, Germany}, ADDRESS = {Bad Malente, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3051}, ISBN = {3-540-22145-X}, YEAR = {2004}, PAGES = {238--251}, ABSTRACT = {This paper develops and compares two tableaux-style proof systems for Peirce algebras. One is a tableau refutation proof system, the other is a proof system in the style of Rasiowa-Sikorski.}, } @INPROCEEDINGS{SchmidtTishkovsky02c, AUTHOR = {Schmidt, Renate A. and Tishkovsky, Dmitry}, EDITOR = {Flesca, Sergio and Greco, Sergio and Leone, Nicola and Ianni, Giovambattista}, TITLE = {Multi-Agent Logic of Dynamic Belief and Knowledge}, BOOKTITLE = {Proceedings of the 8th European Conference on Logics in Artificial Intelligence (JELIA)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Cosenza, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2424}, YEAR = {2002}, PAGES = {38--49}, ABSTRACT = {This paper proposes a family of logics for reasoning about the dynamic activities and informational attitudes, i.e.\ the beliefs and knowledge, of agents. The logics are based on a new formalisations and semantics of the test operator of propositional dynamic logic and a representation of actions which distinguishes abstract actions from concrete actions. The new test operator, called informational test, can be used to formalise the beliefs and knowledge of particular agents as dynamic modalities. This approach is consistent with the formalisation of the agents' beliefs and knowledge as K(D)45 and S5 modalities. Properties concerning the preservation of informativeness, truthfulness and belief are proved for a derivative of the informational test operator. It is shown that common belief and common knowledge can be expressed in these logics. As a consequence, these logics are more expressive than propositional dynamic logic with an extra modality for belief or knowledge. However, the logics are still decidable and in 2EXPTIME. Versions of the considered logics express natural additional properties of beliefs or knowledge and interaction of beliefs or knowledge with actions. A simulation of PDL is constructed in one of these extensions.}, } @UNPUBLISHED{SchmidtTishkovsky02e, AUTHOR = {Schmidt, Renate A. and Tishkovsky, Dmitry}, TITLE = {Multi-Agent Logic of Dynamic Belief and Knowledge}, MONTH = {May}, YEAR = {2003}, PAGES = {34}, NOTE = {Submitted for publication.}, ABSTRACT = {This paper investigates a family of logics for reasoning about the dynamic activities and informational attitudes of agents, namely the agents' beliefs and knowledge. The logics are based on a new formalisation and semantics of the test operator of propositional dynamic logic and a representation of actions which distinguishes abstract actions from concrete actions. The new test operator, called informational test, can be used to formalise the beliefs and knowledge of particular agents as dynamic modalities. This approach is consistent with the formalisation of the agents' beliefs and knowledge as K(D)45 and S5 modalities. Properties concerning the preservation of informativeness, truthfulness and belief are proved for a derivative of the informational test operator. It is shown that common belief and common knowledge can be expressed in the considered logics. This means, the logics are more expressive than propositional dynamic logic with an extra modality for belief or knowledge. The logics remain decidable and belong to 2EXPTIME. Versions of the considered logics express natural additional properties of beliefs or knowledge and interaction of beliefs or knowledge with actions. It is shown a simulation of PDL can be constructed in one of these extensions.}, } @INCOLLECTION{SchmidtTishkovsky03a, AUTHOR = {Schmidt, Renate A. and Tishkovsky, Dmitry}, EDITOR = {Balbiani, Philippe and Suzuki, Nobu-Yuki and Wolter, Frank and Zakharyaschev, Michael}, TITLE = {Combining Dynamic Logic and Doxastic Modal Logics}, BOOKTITLE = {Advances in Modal Logic}, CHAPTER = {18}, ADDRESS = {London, UK}, PUBLISHER = {King's College London Publications}, VOLUME = {4}, YEAR = {2003}, PAGES = {371--391}, ABSTRACT = {We prove completeness and decidability for a family of combinations of propositional dynamic logic and unimodal doxastic logics in which the modalities may interact. The kind of interactions we consider include two forms of commuting axioms, namely, an axiom similar to the axiom of perfect recall from temporal logic and a Church-Rosser axiom. We investigate the influence of the substitution rule on the properties of these logics and propose a new semantics for the test operator to avoid unwanted side effects caused by the interaction of the classic test operator with the extra axioms.}, } @ARTICLE{SchmidtTishkovsky03c, AUTHOR = {Schmidt, Renate A. and Tishkovsky, Dmitry}, JOURNAL = {Annals of Mathematics and Artificial Intelligence}, TITLE = {Multi-Agent Dynamic Logics with Informational Test}, ADDRESS = {Dordrecht}, NUMBER = {1}, PUBLISHER = {Kluwer}, VOLUME = {42}, ISBN = {1012-2443}, YEAR = {2004}, PAGES = {5--36}, NOTE = {To appear}, ABSTRACT = {This paper investigates a family of logics for reasoning about the dynamic activities and informational attitudes of agents, namely the agents' beliefs and knowledge. The logics are based on a new formalisation and semantics of the test operator of propositional dynamic logic and a representation of actions which distinguishes abstract actions from concrete actions. The new test operator, called informational test, can be used to formalise the beliefs and knowledge of particular agents as dynamic modalities. This approach is consistent with the formalisation of the agents' beliefs and knowledge as K(D)45 and S5 modalities. Properties concerning informativeness, truthfulness and preservation of beliefs are proved for a derivative of the informational test operator. It is shown that common belief and common knowledge can be expressed in the considered logics. This means, the logics are more expressive than propositional dynamic logic with an extra modality for belief or knowledge. The logics remain decidable and belong to 2EXPTIME. Versions of the considered logics express natural additional properties of beliefs or knowledge and interaction of beliefs or knowledge with actions. It is shown that a simulation of PDL can be constructed in one of these extensions.}, } @UNPUBLISHED{SchmidtTishkovskyHustadt02a, AUTHOR = {Schmidt, Renate A. and Tishkovsky, Dmitry and Hustadt, Ullrich}, TITLE = {Interaction between Knowledge, Action and Commitment within Agent Dynamic Logic}, YEAR = {2002}, PAGES = {32}, NOTE = {Submitted for publication.}, ABSTRACT = {This paper considers a new class of agent dynamic logics which provide a formal means of specifying and reasoning about the agents' activities and informational, motivational and practical aspects of the behaviour of the agents. We present a Hilbert-style deductive system for a basic agent dynamic logic and consider a number of extensions of this logic with axiom schemata formalising interactions between knowledge and commitment (expressing an agent's awareness of her commitments), and interactions between knowledge and actions (expressing no learning and persistence of knowledge after actions). The deductive systems are proved sound and complete with respect to a Kripke-style semantics. Each of the considered logics is shown to have the small model property and therefore decidable.}, } @ARTICLE{SchmidtTishkovskyHustadt04a, AUTHOR = {Schmidt, Renate A. and Tishkovsky, Dmitry and Hustadt, Ullrich}, JOURNAL = {Studia Logica}, TITLE = {Interaction between Knowledge, Action and Commitment within Agent Dynamic Logic}, NUMBER = {3}, PUBLISHER = {Kluwer}, VOLUME = {78}, ISBN = {0039-3215}, YEAR = {2004}, PAGES = {381--415}, ABSTRACT = {This paper considers a new class of agent dynamic logics which provide a formal means of specifying and reasoning about the agents' activities and informational, motivational and practical aspects of the behaviour of the agents. We present a Hilbert-style deductive system for a basic agent dynamic logic and consider a number of extensions of this logic with axiom schemata formalising interactions between knowledge and commitment (expressing an agent's awareness of her commitments), and interactions between knowledge and actions (expressing no learning and persistence of knowledge after actions). The deductive systems are proved sound and complete with respect to a Kripke-style semantics. Each of the considered logics is shown to have the small model property and therefore decidable.}, } @MASTERSTHESIS{Schmolzi-Diplom99, AUTHOR = {Schmolzi, Christian}, TITLE = {{Kooperative koevolution{\"a}re Entwicklung von Fuzzy-Reglern}}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {March}, YEAR = {1999}, } @INPROCEEDINGS{She2005, AUTHOR = {Ratschan, Stefan and She, Zhikun}, EDITOR = {Calmet, Jacques and Ida, Tetsuo and Wang, Dongming}, TITLE = {Constraints for Continuous Reachability in the Verification of Hybrid Systems}, BOOKTITLE = {Artificial Intelligence and Symbolic Computation, 8th International Conference, AISC 2006}, PADDRESS = {Berlin, Germany}, ADDRESS = {Beijing, China}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {4120}, ISBN = {978-3-540-39728-1}, YEAR = {2006}, PAGES = {196--210}, NOTE = {This work was partly supported by the German Research Council (DFG) as part of the Transregional Collaborative Research Center "Automatic Verification and Analysis of Complex Systems" (SFB/TR 14 AVACS). See www.avacs.org for more information.}, ABSTRACT = {The method for verification of hybrid systems by constraint propagation based abstraction refinement that we introduced in an earlier paper is based on an over-approximation of continuous reachability information of ordinary differential equations using constraints that do not contain differentiation symbols. The method uses an interval constraint propagation based solver to solve these constraints. This has the advantage that—without complicated algorithmic changes—the method can be improved by just changing these constraints. In this paper, we discuss various possibilities of such changes, we prove some properties about the amount of over-approximations introduced by the new constraints, and provide some timings that document the resulting improvement.}, } @INPROCEEDINGS{She2005b, AUTHOR = {She, Zhikun and Ratschan, Stefan}, TITLE = {Providing a Basin of Attraction to a Target Region by Computation of Lyapunov-like Functions}, BOOKTITLE = {4th IEEE International Conference on Computational Cybernetics}, PADDRESS = {MA, USA}, ADDRESS = {Tallinn, Estonia}, PUBLISHER = {IEEE}, MONTH = {August}, ISBN = {1-4244-0072-4}, DOI = {10.1109/ICCCYB.2006.305705}, YEAR = {2006}, PAGES = {245--249}, ABSTRACT = {In this paper, we present a method for computing a basin of attraction to a target region for non-linear ordinary differential equations. This basin of attraction is ensured by a Lyapunov-like polynomial function that we compute using an interval based branch-and-relax algorithm. This algorithm relaxes the necessary conditions on the coefficients of the Lyapunov-like function to a system of linear interval inequalities that can then be solved exactly, and iteratively reduces the relaxation error by recursively decomposing the state space into hyper-rectangles. Tests on an implementation are promising.}, } @INPROCEEDINGS{She2006b, AUTHOR = {She, Zhikun and Xia, Bican and Xiao, Rong}, EDITOR = {Kovalerchuk, B.}, TITLE = {A Semi-Algebraic Approach for the Computation of Lyapunov Functions}, BOOKTITLE = {2th IASTED International Conference on COMPUTATIONAL INTELLIGENCE}, PADDRESS = {Canada}, ADDRESS = {San Francisco, CA, USA}, PUBLISHER = {ACTA Press}, ISBN = {0-88986-602-3}, YEAR = {2006}, PAGES = {7--12}, ABSTRACT = {In this paper we deal with the problem of computing Lya punov functions for stability verification of differential sys tems. We concern on symbolic methods and start the dis cussion with a classical quantifier elimination model for computing Lyapunov functions in a given polynomial form, especially in quadratic forms. Then we propose a new semi-algebraic method by making advantage of the local property of the Lyapunov function as well as its deriva tive. This is done by first using real solution classifica tion to construct a semi-algebraic system and then solving this semi-algebraic system. Our semi-algebraic approach is more efficient in practice, especially for low-order systems. This efficiency will be evaluated empirically. }, } @MASTERSTHESIS{Smaus96, AUTHOR = {Smaus, Jan-Georg}, TITLE = {Finding Resolution K-Transformations}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {March}, YEAR = {1996}, NOTE = {Jan-Georg Smaus obtained his Diploma in Computer Science from Saarland University in March 1996. The supervisor of the work was Hans J{\"u}rgen Ohlbach}, ABSTRACT = {Resolution K-transformations are faithful transformations between clause sets. The aim is to remove clauses like symmetry or transitivity from a clause set in order to eliminate or reduce recursivity and circularity in this clause set. It is shown that for any set of such clauses, a resolution K-transformation is likely to exist and can be found automatically. Clause K-transformations may be applied to reduce the search space of theorem provers, to eliminate loops in logic programs, to parallelise closure computation algorithms and to support automated complexity analysis.}, } @INPROCEEDINGS{socher91a, AUTHOR = {Socher-Ambrosius, Rolf}, EDITOR = {Book, R. V.}, TITLE = {Boolean Algebra Admits no Convergent Term Rewriting System}, BOOKTITLE = {Proceedings of the 4th International Conference on Rewriting Techniques and Applications (RTA-91)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Como, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {488}, YEAR = {1991}, PAGES = {264--274}, ABSTRACT = {Although there exists a normal form for the theory of Boolean Algebra w.r.t. associativity and commutativity, the so called set of prime implicants, there does not exist a convergent equational term rewriting system for the theory of Boolean Algebra modulo AC. The result seems well-known, but no formal proof exists as yet. In this paper a formal proof of this fact is given.}, } @ARTICLE{socher91b, AUTHOR = {Socher-Ambrosius, Rolf}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {Optimizing the Clausal Normal Form Transformation}, NUMBER = {3}, PUBLISHER = {Kluwer}, VOLUME = {7}, ISBN = {0168-7433}, YEAR = {1991}, PAGES = {325--336}, ABSTRACT = {Resolution based theorem proving systems require the conversion of predicate logic formulae into clausal normal form. The multiplication from disjunctive into conjunctive forms in general produces a lot of tautologous and subsumed clauses, which is relatively hard to recognize in later stages of the proof. In this paper an algorithm is presented that avoids the generation of redundant clauses. It is based on the generation of paths through a matrix and produces the set of prime implicants of the original formula.}, } @ARTICLE{socher91c, AUTHOR = {Socher-Ambrosius, Rolf}, JOURNAL = {Journal of Symbolic Computation}, TITLE = {On the Relation Between Completion Based and Resolution Based Theorem Proving}, NUMBER = {1 \& 2}, VOLUME = {11}, YEAR = {1991}, PAGES = {129--148}, ABSTRACT = {Completion Theorem Proving, as proposed by Hsiang, is based on the observation that proving a first-order formula is equivalent to solving an equational system over a boolean polynomial ring. The latter can be accomplished by completing the set of rewrite rules obtained from the equational system. This method's basic deduction rule is the generation of a new rule from a divergent critical pair obtained by superposition of two rules. This paper relates superpositiexactly once-a result which was given by R. Shostak-but admit completion refutations with this property, that is, such a completion refutation is shorter than any resolution refutation can be. Furthermore, we show by means of Shostak's theorem that the language of rings and ideals is well suited for short and elegant proofs of theorems about resolution deductions.}, } @TECHREPORT{socher91d, AUTHOR = {Socher-Ambrosius, Rolf}, TITLE = {On the {C}hurch-{R}osser Property in Left-Linear Systems}, INSTITUTION = {SUNY at Stony Brook}, TYPE = {{TR} 91/17}, YEAR = {1991}, ABSTRACT = {In this paper three critical pair conditions are given that are sufficient for a finite, left-linear, but not necessarily terminating term rewriting system to have the Church-Rosser property.}, } @INPROCEEDINGS{socher92a, AUTHOR = {Socher-Ambrosius, Rolf}, EDITOR = {Kirchner, H{\'e}l{\`e}ne and Levi, G.}, TITLE = {A Goal Oriented Strategy Based on Completion}, BOOKTITLE = {Proc.~3rd Intern.~Conference on Algebraic and Logic Programming}, PADDRESS = {Berlin, Germany}, ADDRESS = {Volterra, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {632}, YEAR = {1992}, PAGES = {435--445}, NOTE = {Also available as Research Report MPI-I-92-206}, ABSTRACT = {In this paper, a paramodulation calculus for equational reasoning is presented that combines the advantages of both Knuth-Bendix completion and goal directed strategies like the set of support strategy. Its soundness and completeness is proved, and finally the practical aspects of this method are discussed.}, } @ARTICLE{socher92b, AUTHOR = {Socher-Ambrosius, Rolf}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {How to Avoid the Derivation of Redundant Clauses in Reasoning Systems}, NUMBER = {1}, PUBLISHER = {Kluwer}, VOLUME = {9}, ISBN = {0168-7433}, YEAR = {1992}, PAGES = {325--336}, ABSTRACT = {This paper addresses two problems concerning the issue of redundant information in resolution based reasoning systems. The first one deals with the question how the derivation of redundant clauses, such as duplicates or instances of already retained clauses, can be substantially reduced. The second one asks for a criterion to decide, which clauses need not be tested for reduncancy. In this paper we consider a particular kind of reduncancy, which we call {\em ancestor subsumption}, that is the subsumption of a resolvent by one of its ancestors. We give a complete syntactic characterization of clause sets producing ancestor subsumed clauses. This characterization partially answers the two questions. First, if a clause set is known to exclude ancestor subsumption, linear resolution turns out to be a preferable strategy in order to reduce the generation of subsumed clauses. Concerning the second question, this result allows a suitable restriction of the-usually very expensive-subsumption test. Finally, we show that in particular cases those clauses that account for the occurrence of ancestor subsumption can be excluded from the resolution process. SAM's lemma will serve as an example for demonstrating various possibilities to remove reduncancy-generating clauses.}, } @INPROCEEDINGS{Socher93a, AUTHOR = {Socher-Ambrosius, Rolf}, EDITOR = {Voronkov, Andrei}, TITLE = {Unification in Order-Sorted Logic with Term Declarations}, BOOKTITLE = {Proceedings of the 4th Conference on Logic Programming and Automated Reasoning (LPAR-93)}, PADDRESS = {Berlin, Germany}, ADDRESS = {St. Petersburg, Russia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {698}, YEAR = {1993}, PAGES = {301--308}, ABSTRACT = {This paper provides two results concerning Order-Sorted Logic with Term Declarations. First, we show that linear term declarations can be transformed conservatively into function declarations, thus yielding elementary signatures. This provides a simple proof of the well known fact that unification in linear signatures is decidable. A similar transformation exists for semi-linear term declarations, resulting in shallow term declarations. Secondly, we provide an inference system transforming sort constraints over an arbitrary signature into almost solved form. The step from almost solved forms to solved forms requires a procedure to decide emptiness of sort intersections, which is not possible in general. This shows that it is the sort intersection problem that accounts for the undecidability of unification in signatures with term declarations.}, } @INPROCEEDINGS{socher94a, AUTHOR = {Socher-Ambrosius, Rolf}, EDITOR = {Bundy, Alan}, TITLE = {A Refined Version of General {E}-Unification}, BOOKTITLE = {Proceedings of the 12th International Conference on Automated Deduction (CADE-12)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Nancy, France}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {814}, YEAR = {1994}, PAGES = {665--677}, } @INPROCEEDINGS{Sofronie-cade-05, AUTHOR = {Sofronie-Stokkermans, Viorica}, EDITOR = {Nieuwenhuis, Robert}, TITLE = {Hierarchic reasoning in local theory extensions}, BOOKTITLE = {Automated deduction - CADE-20 : 20th International Conference on Automated Deduction}, PADDRESS = {Berlin, Germany}, ADDRESS = {Tallinn, Estonia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {3632}, ISBN = {0302-9743}, YEAR = {2005}, PAGES = {219--234}, ABSTRACT = {We show that for special types of extensions of a base theory, which we call {\em local}, efficient hierarchic reasoning is possible. We identify situations in which it is possible, for an extension ${\cal T}_1$ of a theory ${\cal T}_0$, to express the decidability and complexity of the universal theory of ${\cal T}_1$ in terms of the decidability resp.\ complexity of suitable fragments of the theory ${\cal T}_0$ (universal or $\forall \exists$). These results apply to theories related to data types, but also to certain theories of functions from mathematics.}, } @INPROCEEDINGS{Sofronie-ijcar-06, AUTHOR = {Sofronie-Stokkermans, Viorica}, EDITOR = {Furbach, Ulrich and Shankar, Natarajan}, TITLE = {Interpolation in local theory extensions}, BOOKTITLE = {Proceedings of IJCAR 2006}, PADDRESS = {New York}, ADDRESS = {Seattle, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {4130}, YEAR = {2006}, PAGES = {235--250}, ABSTRACT = {Many problems in mathematics and computer science (e.g. in verification, or when reasoning in and about distributed databases) can be reduced to proving the satisfiability of conjunctions of (ground) literals modulo a background theory. This theory can, for instance, be the extension of a base theory with additional functions or a combination of theories. It is therefore very important to find efficient methods for checking the unsatisfiability of ground formulae in such complex theories. However, it is often equally important to find local causes for inconsistency. Such information is usually provided by interpolants. In this paper we study interpolation in local extensions of a base theory ${\cal T}_0$. In such extensions efficient hierarchical reasoning -- in which a prover for the base theory is used as a black box -- is possible. We identify situations in which it is possible to obtain interpolants in a hierarchical manner, by using a prover and a procedure for generating interpolants in ${\cal T}_0$ as `black-boxes' in order to generate interpolants in the extension. We provide several examples of such theories, and discuss their applications in verification or knowledge representation.}, } @INPROCEEDINGS{Sofronie-Stokkermans-cade2000, AUTHOR = {Sofronie-Stokkermans, Viorica}, EDITOR = {McAllester, David}, TITLE = {On unification for bounded distributive lattices}, BOOKTITLE = {Proceedings of the 17th International Conference on Automated Deduction (CADE-17)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Pittsburgh, Pennsylvania, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1831}, ISBN = {3-540-67664-3}, YEAR = {2000}, PAGES = {465--481}, ABSTRACT = {We give a resolution-based procedure for deciding unifiability in the variety of bounded distributive lattices. The main idea is to use a structure-preserving translation to clause form to reduce the problem of testing the satisfiability of a unification problem ${\cal S}$ to the problem of checking the satisfiability of a set $\Phi_{\cal S}$ of (constrained) clauses. These ideas can be used for unification with free constants and for unification with linear constant restrictions. Complexity issues are also addressed.}, } @ARTICLE{Sofronie-Stokkermans-dam-06, AUTHOR = {Sofronie-Stokkermans, Viorica}, JOURNAL = {Discrete Applied Mathematics}, TITLE = {Automated theorem proving by resolution in non-classic logics}, PUBLISHER = {Elsevier}, ISBN = {0166-218X}, YEAR = {2007}, NOTE = {To appear, probably in 2007.}, ABSTRACT = {This paper is an overview of a variety of results, all centered around a common theme, namely embedding of non-classical logics into first order logic and resolution theorem proving. We present several classes of non-classical logics, many of which are of great practical relevance in knowledge representation, which can be translated into tractable and relatively simple fragments of classical logic. In this context, we show that refinements of resolution can often be used successfully for automated theorem proving, and in many interesting cases yield optimal decision procedures.}, } @INPROCEEDINGS{Sofronie-Stokkermans-dualities1999, AUTHOR = {Sofronie-Stokkermans, Viorica}, EDITOR = {Vaz de Carvalho, J{\'u}lia and Ferreirim, Isabel}, TITLE = {Priestley representation for distributive lattices with operators and applications to automated theorem proving}, BOOKTITLE = {Dualities, Interpretability and Ordered Structures}, TYPE = {Extended Abstract}, PADDRESS = {Lisbon}, ADDRESS = {Lisbon, Portugal}, PUBLISHER = {Centro de 'Algebra da Universidade de Lisboa}, YEAR = {1999}, PAGES = {43--54}, ABSTRACT = {We present an extension of the Priestley representation theorem to distributive lattices with operators. We then point out how it can be used for automated theorem proving in certain finitely-valued logics.}, } @INPROCEEDINGS{Sofronie-Stokkermans-ftp2000, AUTHOR = {Sofronie-Stokkermans, Viorica}, TITLE = {Resolution-based theorem proving for {SHn-logics}}, BOOKTITLE = {Automated Deduction in Classical and Non-Classical Logic (Selected Papers of FTP'98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Vienna, Austria}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1761}, ISBN = {3-540-67190-0}, YEAR = {2000}, PAGES = {268--282}, NOTE = {%Extended version of [Sofronie1998b]. }, ABSTRACT = {In this paper we illustrate by means of an example, namely $SHn$-logics, a method for translation to clause form and automated theorem proving for first-order many-valued logics based on distributive lattices with operators.}, } @INPROCEEDINGS{Sofronie-Stokkermans-getco-06, AUTHOR = {Sofronie-Stokkermans, Viorica}, TITLE = {Sheaves and geometric logic in concurrency}, BOOKTITLE = {Proceedings of the Eighth Workshop on Geometric and Topological Methods in Concurrency (GETCO 2006)}, PADDRESS = {-}, ADDRESS = {Bonn, Germany}, PUBLISHER = {-}, MONTH = {August}, YEAR = {2006}, ABSTRACT = {In this paper we present an overview of results that show that states, transitions and behavior of concurrent systems can often be modeled as sheaves over a suitable topological space. In such contexts, geometric logic can be used to test whether (and describe which) local properties, of individual systems, are preserved, at a global level, when interconnecting the systems.}, } @PHDTHESIS{Sofronie-Stokkermans-hab04, AUTHOR = {Sofronie-Stokkermans, Viorica}, TITLE = {Algebraic and logical methods in automated theorem proving and in the study of concurrency}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Habilitation thesis}, MONTH = {November}, YEAR = {2004}, NOTE = {cumulative habilitation, no publication.}, ABSTRACT = {Vorstellungsvortrag ------------------- Abstract: The applications of algebra and logic in computer science are particularly abundant nowadays; in fact logic is often called "the calculus of computer science". On the other hand, the development of computer science has a strong impact on the research in algebra and logic, and in particular on the research in computational mathematics and automated theorem proving. \smallskip In this talk I will present two, strongly interrelated, directions of my recent research, which reflect some of the links between algebra, logic and computer science emphasized above: \begin{itemize} \item Decompositions of algebraic structures in terms of simpler structures, and applications to automated theorem proving. \item A study of interaction in complex systems, and applications to modular checking of certain properties of systems obtained by composing simpler systems. \end{itemize} Antrittsvorlesung ----------------- Abstract: One of the most important problems in computer science is to identify decidable and tractable fragments of (first- or higher-order) logic, and to develop efficient deductive calculi for these fragments. However, in most real-life applications it is necessary to consider combinations of theories which are, usually, extensions of a shared base theory. Two important questions arise in this context: \begin{itemize} \item Assume that we have a complete prover for a logical theory. Can one use this prover as a ``black-box'' to prove theorems in an extension of the theory? \item Assume that we have complete provers for two theories. Can we obtain a complete prover for their combination, by using the provers of the components as ``black-boxes''? \end{itemize} In this talk we present several situations in which hierarchical and modular reasoning is possible, and point out similarities and differences between various approaches to modular theorem proving in combinations of logical theories.}, } @INPROCEEDINGS{Sofronie-Stokkermans-ismvl-2004, AUTHOR = {Sofronie-Stokkermans, Viorica}, TITLE = {Resolution-based decision procedures for the positive theory of some finitely generated varieties of algebras}, BOOKTITLE = {Proceedings of the 34th International Symposium on Multiple-Valued Logic (ISMVL-2004)}, ORGANIZATION = {IEEE}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Toronto, Canada}, PUBLISHER = {IEEE Computer Society}, YEAR = {2004}, PAGES = {32--37}, ABSTRACT = {In this paper we give resolution-based decision procedures for the positive theory of certain finitely-generated varieties of algebras. The method is based on the existence of representation theorems for such classes of algebras.}, } @INPROCEEDINGS{Sofronie-Stokkermans-jim-2003, AUTHOR = {Sofronie-Stokkermans, Viorica}, EDITOR = {Nadif, Mohamed and Napoli, Amedeo and SanJuan, Eric and Sigayret, Alain}, TITLE = {Automated theorem proving by resolution in non-classical logics}, BOOKTITLE = {Fourth International Conference Journees de l'Informatique Messine: Knowledge Discovery and Discrete Mathematics (JIM-03)}, PADDRESS = {Rocquencourt, France}, ADDRESS = {Metz, France}, PUBLISHER = {INRIA}, ISBN = {2-7261-1256-0}, YEAR = {2003}, PAGES = {151--167}, NOTE = {Invited paper}, ABSTRACT = {We present several classes of non-classical logics (many of which are practically relevant in knowledge representation) which can be translated into tractable and relatively simple fragments of classical logic. In this context, refinements of resolution can be often used successfully for automated theorem proving, and in many cases yield optimal decision procedures.}, } @ARTICLE{Sofronie-Stokkermans-jsc-2003, AUTHOR = {Sofronie-Stokkermans, Viorica}, JOURNAL = {Journal of Symbolic Computation}, TITLE = {Resolution-based decision procedures for the universal theory of some classes of distributive lattices with operators}, ADDRESS = {Amsterdam, The Netherlands}, NUMBER = {6}, PUBLISHER = {Elsevier}, VOLUME = {36}, ISBN = {0747-7171}, YEAR = {2003}, PAGES = {891--924}, ABSTRACT = {We establish a link between the satisfiability of universal sentences with respect to classes of distributive lattices with operators and their satisfiability with respect to certain classes of relational structures. This justifies a method for structure-preserving translation to clause form of universal sentences in such classes of algebras. We show that refinements of resolution yield decision procedures for the universal theory of some such classes. In particular, we obtain exponential space and time decision procedures for the universal clause theory of (i) the class of all bounded distributive lattices with operators satisfying a set of (generalized) residuation conditions, (ii) the class of all bounded distributive lattices with operators, and a doubly-exponential time decision procedure for the universal clause theory of the class of all Heyting algebras.}, } @INCOLLECTION{Sofronie-Stokkermans-mvl-2003, AUTHOR = {Sofronie-Stokkermans, Viorica}, EDITOR = {Fitting, Melvin and Orlowska, Ewa}, TITLE = {Representation Theorems and the Semantics of Non-classical Logics, and Applications to Automated Theorem Proving}, BOOKTITLE = {Beyond Two: Theory and Applications of Multiple Valued Logic}, CHAPTER = {3}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, MONTH = {January}, SERIES = {Studies in Fuzziness and Soft Computing}, VOLUME = {114}, ISBN = {3-7908-1541-1}, YEAR = {2003}, PAGES = {59--100}, ABSTRACT = {We give a uniform presentation of representation and decidability results related to the Kripke-style semantics of several non-classical logics. We show that a general representation theorem (which has as particular instances the representation theorems as algebras of sets for Boolean algebras, distributive lattices and semilattices) extends in a natural way to several classes of operators and allows to establish a relationship between algebraic and Kripke-style models. We illustrate the ideas on several examples. We conclude by showing how the Kripke-style models thus obtained can be used (if first-order axiomatizable) for automated theorem proving by resolution for some non-classical logics.}, } @INPROCEEDINGS{Sofronie-Stokkermans-tableaux-2002, AUTHOR = {Sofronie-Stokkermans, Viorica}, EDITOR = {Egly, Uwe and Ferm{\"u}ller, Christian}, TITLE = {On uniform word problems involving bridging operators on distributive lattices}, BOOKTITLE = {Automated Reasoning with Analytic and Related Methods : International Conference, TABLEAUX 2002}, PADDRESS = {Berlin, Germany}, ADDRESS = {Copenhagen, Denmark}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2381}, ISBN = {3-540-43929-3}, YEAR = {2002}, PAGES = {235--250}, ABSTRACT = {In this paper we analyze some fragments of the universal theory of distributive lattices with many sorted bridging operators. Our interest in such algebras is motivated by the fact that, in description logics, numerical features are often expressed by using maps that associate numerical values to sets (more generally, to lattice elements). We first establish a link between satisfiability of universal sentences with respect to algebraic models and satisfiability with respect to certain classes of relational structures. We use these results for giving a method for translation to clause form of universal sentences, and provide some decidability results based on the use of resolution or hyperresolution. Links between hyperresolution and tableau methods are also discussed, and a tableau procedure for checking satisfiability of formulae of type $t_1 \leq t_2$ is obtained by using a hyperresolution calculus.}, } @ARTICLE{Sofronie-Stokkermans-unif-05, AUTHOR = {Sofronie-Stokkermans, Viorica}, JOURNAL = {ACM Transactions on Computational Logic}, TITLE = {On unification for bounded distributive lattices}, NUMBER = {2}, PUBLISHER = {ACM}, MONTH = {April}, VOLUME = {8}, YEAR = {2007}, ABSTRACT = {We give a method for deciding unifiability in the variety of bounded distributive lattices. For this, we reduce the problem of deciding whether a unification problem ${\cal S}$ has a solution to the problem of checking the satisfiability of a set $\Phi_{\cal S}$ of ground clauses. This is achieved by using a structure-preserving translation to clause form. The satisfiability check can then be performed either by a resolution-based theorem prover or by a SAT checker. We apply the method to unification with free constants and to unification with linear constant restrictions, and show that, in fact, it yields a decision procedure for the positive theory of the variety of bounded distributive lattices. We also consider the problem of unification over (i.e.\ in an algebraic extension of) the free lattice. Complexity issues are also addressed.}, } @ARTICLE{Sofronie-Stokkermans1999, AUTHOR = {Sofronie-Stokkermans, Viorica}, JOURNAL = {Multiple-Valued Logic - An International Journal}, TITLE = {Automated Theorem Proving by Resolution for Finitely-Valued Logics Based on Distributive Lattices with Operators}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {3/4}, PUBLISHER = {Gordon and Breach}, MONTH = {March}, VOLUME = {6}, ISBN = {1023-6627}, YEAR = {2001}, PAGES = {289--344}, NOTE = { }, ABSTRACT = {In this paper we present a method for automated theorem proving in finitely-valued logics whose algebra of truth values is a distributive lattice with operators. The method uses the Priestley dual of the algebra of truth values instead of the algebra itself (this dual is used as a finite set of possible worlds). We first present a procedure that constructs, for every formula $\phi$ in the language of such a logic, a set $\Phi$ of clauses such that $\phi$ is a theorem if and only if $\Phi$ is unsatisfiable. Compared to related approaches, the method presented here leads in many cases to a reduction of the number of clauses that are generated, especially when the set of truth values is not linearly ordered. We then discuss several possibilities for checking the unsatisfiability of $\Phi$, among which a version of signed hyperresolution, and give several examples. }, } @INPROCEEDINGS{Sofronie-Stokkermans1999-cade, AUTHOR = {Sofronie-Stokkermans, Viorica}, EDITOR = {Ganzinger, Harald}, TITLE = {On the Universal Theory of Varieties of Distributive Lattices with Operators: Some Decidability and Complexity Results}, BOOKTITLE = {Proceedings of the 16th International Conference on Automated Deduction (CADE-16)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Trento, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1632}, YEAR = {1999}, PAGES = {157--171}, ABSTRACT = {In this paper we give a method for automated theorem proving in the universal theory of certain varieties of distributive lattices with well-behaved operators. For this purpose, we use extensions of Priestley's representation theorem for distributive lattices. We first establish a link between satisfiability of universal sentences with respect to varieties of distributive lattices with operators and satisfiability with respect to certain classes of relational structures. We then use these results for giving a method for translation to clause form of universal sentences in such varieties, and obtain decidability and complexity results for the universal theory of some such varieties. The advantage is that we avoid the explicit use of the full algebraic structure of such lattices, instead using sets endowed with a reflexive and transitive relation and with additional functions and relations. We first studied this type of relationships in the context of finitely-valued logics and then extended the ideas to more general non-classical logics. This paper shows that the idea is much more general. In particular, the method presented here subsumes both existing methods for translating modal logics to classical logic and methods for automated theorem proving in finitely-valued logics based on distributive lattices with operators. }, } @INPROCEEDINGS{Sofronie-Stokkermans1999-fct, AUTHOR = {Sofronie-Stokkermans, Viorica and Stokkermans, Karel}, EDITOR = {Ciobanu, Gabriel and Paun, Gheorghe}, TITLE = {Modeling Interaction by Sheaves and Geometric Logic}, BOOKTITLE = {Proceedings of the 12th International Symposium Fundamentals of Computation Theory (FCT-99)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Iasi, Romania}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1684}, ISBN = {3-540-66412-2}, YEAR = {1999}, PAGES = {512--523}, ABSTRACT = {In this paper we show that, given a family of interacting systems, many notions which are important for expressing properties of systems can be modeled as sheaves over a suitable topological space. In such contexts, geometric logic can be used to test whether ``local'' properties can be lifted to a global level. We develop a way to use this method in the study of interacting systems, illustrated by examples.}, } @INPROCEEDINGS{Sofronie-Stokkermans1999-ismvl, AUTHOR = {Sofronie-Stokkermans, Viorica}, TITLE = {Representation Theorems and Automated Theorem Proving in Non-Classical Logics}, BOOKTITLE = {Proceedings of the 29th IEEE International Symposium on Multiple-Valued Logic (ISMVL-99)}, ORGANIZATION = {IEEE Computer Society}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Freiburg im Breisgau, Germany}, PUBLISHER = {IEEE}, MONTH = {May}, ISBN = {0-7695-0161-3}, YEAR = {1999}, PAGES = {242--247}, ABSTRACT = {In this paper we present a method for automated theorem proving in non-classical logics having as algebraic models bounded distributive lattices with certain types of operators. The idea is to use results from Priestley duality for distributive lattices with operators in order to define a class of Kripke-style models with respect to which the logic is sound and complete. If this class of Kripke-style models is elementary, it can then be used for a translation to clause form; satisfiability of the resulting clauses can be checked by resolution. We illustrate the general ideas by several examples, one of which is presented in detail.}, } @INPROCEEDINGS{Sofronie-Stokkermans1999-lmps, AUTHOR = {Sofronie-Stokkermans, Viorica}, EDITOR = {Cachro, Jacek and Kijania-Placek, Katarzyna}, TITLE = {Resolution-based theorem proving for non-classical logics based on distributive lattices with operators}, BOOKTITLE = {Proceedings of the 11th International Congress of Logic, Methodology and Philosophy of Science. Volume of abstracts}, TYPE = {Abstract}, PADDRESS = {Cracow, Poland}, ADDRESS = {Cracow, Poland}, PUBLISHER = {The Faculty of Philosophy, Jagellonian University}, MONTH = {August}, ISBN = {83-912252-0-8}, YEAR = {1999}, PAGES = {481--481}, } @INCOLLECTION{Sofronie-Stokkermans2000-atlas-1, AUTHOR = {Iturrioz, Luisa and Sofronie-Stokkermans, Viorica}, EDITOR = {Iturrioz, Luisa and Orlowska, Ewa and Turunen, Esko}, TITLE = {{SHn-algebras} ({Symmetric} {Heyting} algebras of order n)}, BOOKTITLE = {COST Action 15 (Many-Valued Logics for Computer Science Applications) ATLAS of Many-Valued Structures}, TYPE = {Technical Report}, ADDRESS = {Tampere}, NUMBER = {75}, PUBLISHER = {Tampere University of Technology (Mathematics)}, MONTH = {January}, SERIES = {Department of Information Technology. Mathematics Report}, ISBN = {952-150-386-6}, YEAR = {2000}, PAGES = {1--11}, } @INCOLLECTION{Sofronie-Stokkermans2000-atlas-2, AUTHOR = {Sofronie-Stokkermans, Viorica}, EDITOR = {Iturrioz, Luisa and Orlowska, Ewa and Turunen, Esko}, TITLE = {Some properties of {Kleene} algebras}, BOOKTITLE = {COST Action 15 (Many-Valued Logics for Computer Science Applications) ATLAS of Many-Valued Structures}, TYPE = {Technical Report}, ADDRESS = {Tampere}, NUMBER = {75}, PUBLISHER = {Tampere University of Technology (Mathematics)}, MONTH = {January}, SERIES = {Department of Information Technology. Mathematics Report}, ISBN = {952-150-386-6}, YEAR = {2000}, PAGES = {1--7}, } @INPROCEEDINGS{Sofronie-Stokkermans2001-ismvl, AUTHOR = {Sofronie-Stokkermans, Viorica}, TITLE = {Representation theorems and the semantics of (semi)lattice-based logics}, BOOKTITLE = {Proceedings of the 31st IEEE International Symposium on Multiple-Valued Logics}, ORGANIZATION = {IEEE Computer Society, Institute of Computer Science Polish Academy of Sciences}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Warsaw, Poland}, PUBLISHER = {IEEE}, ISBN = {0-7695-1083-3}, YEAR = {2001}, PAGES = {125--134}, NOTE = { }, ABSTRACT = {This paper gives a unified presentation of various non-classical logics. We show that a general representation theorem (which has as particular instances the representation theorems as algebras of sets for Boolean algebras, distributive lattices and semilattices) allows to establish a relationship between algebraic models and Kripke-style models, and illustrate the ideas on several examples. Based on this, we present a method for automated theorem proving by resolution in such logics. Other representation theorems, as algebras of sets or as algebras of relations, as well as relational models are also mentioned. }, } @INPROCEEDINGS{Sofronie-verify-06, AUTHOR = {Sofronie-Stokkermans, Viorica}, EDITOR = {Autexier, Serge and Mantel, Heiko}, TITLE = {Local reasoning in verification}, BOOKTITLE = {Proceedings of VERIFY'06: Verification Workshop}, PADDRESS = {-}, ADDRESS = {Seattle, USA}, PUBLISHER = {-}, MONTH = {August}, YEAR = {2006}, PAGES = {128--145}, ABSTRACT = {he goal of this paper is to illustrate the wide applicability in verification of results on local reasoning, and especially on hierarchical reasoning in local theory extensions. The paper contains a survey of our results on reasoning in local theory extensions, ranging from characterizations of locality to interpolation. In addition, several examples are provided, emphasizing theories occurring in a natural way in verification. We give several examples -- some already existing in the literature, others obtained during the work in the AVACS project -- of application domains where such theories occur in a natural way.}, } @ARTICLE{Sofronie1997a, AUTHOR = {Sofronie-Stokkermans, Viorica}, JOURNAL = {Multiple-Valued Logic - An International Journal}, TITLE = {Priestley Duality for {SHn-algebras} and Applications to the Study of {Kripke-style} Models for {SHn-logics}}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {4}, PUBLISHER = {Gordon and Breach}, VOLUME = {5}, ISBN = {1023-6627}, YEAR = {2000}, PAGES = {281--305}, ABSTRACT = {The main goal of this paper is to show that the Priestley duality for SHn-algebras can help to establish a link between the algebraic and Kripke-style semantics for SHn-logics. We present a Priestley duality theorem for SHn-algebras, and note that the dual space of an SHn-algebra satisfies in particular the properties of a Kripke model for SHn-logics. We then show that Priestley duality can help in proving the soundness and completeness of SHn-logics with respect to the class of SHn-frames in a direct way, by using only soundness and completeness of SHn-logics with respect to the variety of SHn-algebras. }, } @ARTICLE{Sofronie1997b, AUTHOR = {Sofronie-Stokkermans, Viorica}, JOURNAL = {Studia Logica}, TITLE = {Duality and Canonical Extensions of Bounded Distributive Lattices with Operators and Applications to the Semantics of Non-Classical Logics. {Part I}}, ADDRESS = {Dordrecht, the Netherlands}, NUMBER = {1}, PUBLISHER = {Kluwer}, MONTH = {February}, VOLUME = {64}, ISBN = {0039-3215}, YEAR = {2000}, PAGES = {93--132}, ABSTRACT = {The main goal of this paper is to explain the link between the algebraic and the Kripke-style models for certain classes of propositional logics. We start by presenting a Priestley-type duality for distributive lattices endowed with a general class of well-behaved operators. We then show that finitely-generated varieties of distributive lattices with operators are closed under canonical embedding algebras. The results are used in the second part of the paper to construct topological and non-topological Kripke-style models for logics that are sound and complete with respect to varieties of distributive lattices with operators in the above-mentioned classes. }, } @ARTICLE{Sofronie1997c, AUTHOR = {Sofronie-Stokkermans, Viorica}, JOURNAL = {Studia Logica}, TITLE = {Duality and Canonical Extensions of Bounded Distributive Lattices with Operators and Applications to the Semantics of Non-Classical Logics. {Part II}}, ADDRESS = {Dordrecht, the Netherlands}, NUMBER = {2}, PUBLISHER = {Kluwer}, MONTH = {March}, VOLUME = {64}, ISBN = {0039-3215}, YEAR = {2000}, PAGES = {151--172}, ABSTRACT = {In this paper we explain the link between the algebraic models and the Kripke-style models for certain classes of propositional non-classical logics. We consider logics that are sound and complete with respect to varieties of distributive lattices with certain classes of well-behaved operators for which a Priestley-style duality holds, and present a way of constructing topological and non-topological Kripke-style models for these types of logics. Moreover, we show that, under certain additional assumptions on the variety of the algebraic models of the given logics, soundness and completeness with respect to these classes of Kripke-style models follows by using entirely algebraical arguments from the soundness and completeness of the logic with respect to its algebraic models. }, } @INPROCEEDINGS{Sofronie1998a, AUTHOR = {Sofronie-Stokkermans, Viorica}, EDITOR = {Prade, Henri}, TITLE = {On Translation of Finitely-Valued Logics to Classical First-Order Logic}, BOOKTITLE = {Proceedings of the 13th European Conference on Artificial Intelligence (ECAI-98)}, PADDRESS = {Chichester, USA}, ADDRESS = {Brighton, UK}, PUBLISHER = {Wiley}, ISBN = {0-471-98431-0}, YEAR = {1998}, PAGES = {410--411}, ABSTRACT = {The main goal of this paper is to give a better understanding of existing many-valued resolution procedures, and thus help to improve the efficiency of automated theorem proving in finitely-valued logics. First, we briefly present a method for translation to clause form in finitely-valued logics based on distributive lattices with operators, which uses the Priestley dual of the algebra of truth values. We show that the unsatisfiability of the set of signed clauses thus obtained can be checked by a version of signed negative hyperresolution. This extends the results established by H\"ahnle in the case of regular logics, where the set of truth values is linearly ordered. As in the case of regular hyperresolution, also our version of signed hyperresolution is surprisingly similar to the classical version. In the second part of the paper we explain why regular logics and the logics we consider are so well-behaved. We show that in both cases the translation to clause form is actually a translation to classical logic, and that soundness and completeness of various refinements of the (signed) resolution procedure follow as a consequence of results from first-order logic. Decidability and complexity results for signed clauses follow as well, by using results from first-order logic. This explains and extends earlier results on theorem proving in finitely-valued logics.}, } @TECHREPORT{Sofronie1998b, AUTHOR = {Sofronie-Stokkermans, Viorica}, TITLE = {Resolution-based Theorem Proving for SHn-Logics}, INSTITUTION = {Technische Universit{\"a}t Wien}, TYPE = {Technical Report}, ADDRESS = {Vienna, Austria}, NUMBER = {E1852-GS-981}, MONTH = {November}, YEAR = {1998}, PAGES = {224--233}, NOTE = {an extended version will appear in LNCS (subseries LNAI); Proceedings of FTP'98}, ABSTRACT = {In this paper we illustrate by means of an example, namely $SHn$-logics, a method for translation to clause form and automated theorem proving for first-order many-valued logics based on distributive lattices with operators.}, } @INPROCEEDINGS{Sofronie1998c, AUTHOR = {Sofronie-Stokkermans, Viorica}, EDITOR = {Eklund, Patrick and Escalada-Imaz, Gonzalo and Haehnle, Reiner and Vojtas, Peter}, TITLE = {Representation Theorems and Automated Theorem Proving in Certain Classes of Non-Classical Logics}, BOOKTITLE = {Proceedings of the Workshop on Many-Valued Logic for AI Applications (ECAI-98)}, PADDRESS = {Brighton, UK}, ADDRESS = {Brighton, UK}, PUBLISHER = {ECAI}, MONTH = {August}, YEAR = {1998}, ABSTRACT = {The main goal of this paper is to present a method for translation to clause form in finitely-valued logics having as algebras of truth values distributive lattices with certain types of operators. The method uses the Priestley dual of the algebra of truth values. We illustrate these general ideas by several examples, and show that the general complexity can be further improved by using the structure of particular algebras of truth values. We then show that these ideas are actually much more general: we further develop one of our previous ideas where we showed that Priestley duality is useful in better understanding the link between algebraic and Kripke-style models for certain non-classical logics, and give several examples.}, } @TECHREPORT{Struth94a, AUTHOR = {Struth, Georg}, TITLE = {Philosophical Logics: A Survey and a Bibliography}, INSTITUTION = {DFKI (German Research Institute for Artificial Intelligence)}, TYPE = {Research Report}, ADDRESS = {Saarbr{\"u}cken, Germany}, NUMBER = {RR-94-17}, YEAR = {1994}, PAGES = {58}, ABSTRACT = {Intensional logics attract the attention of researchers from differing academic backgrounds and various scientific interests. My aim is to sketch the philosophical background of alethic, epistemic, doxastic and deontic logics, their formal and metaphysical presumptions and their various problems and paradoxes, without attempting formal rigor. A bibliography, concise on philosophical writings, is meant to allow the reader's access to the maze of literature in the field.}, } @INPROCEEDINGS{Struth94b, AUTHOR = {Struth, Georg}, EDITOR = {Kunze, J. and Stoyan, H.}, TITLE = {Intensionality, Possible Worlds and Propositional Attitudes: Formal and Philosophical Foundations of Modal Semantics}, BOOKTITLE = {KI-94 Workshops: Extended Abstracts}, ORGANIZATION = {18. Deutsche Jahrestagung f{\"u}r K{\"u}nstliche Intelligenz}, PADDRESS = {Bonn, Germany}, ADDRESS = {Saarbr{\"u}cken, Germany}, PUBLISHER = {Gesellschaft f{\"u}r Informatik}, YEAR = {1994}, PAGES = {108--109}, } @INPROCEEDINGS{Struth97, AUTHOR = {Struth, Georg}, EDITOR = {Comon, Hubert}, TITLE = {On the Word Problem for Free Lattices}, BOOKTITLE = {Proceedings of the 8th International Conference on Rewriting Techniques and Applications (RTA-97)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Sitges, Spain}, PUBLISHER = {Springer}, MONTH = {June}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1232}, YEAR = {1997}, PAGES = {128--141}, ABSTRACT = { We prove completeness of a rewrite-based algorithm for the word problem in the variety of lattices and discuss the method of non-symmetric completion with regard to this variety.}, } @PHDTHESIS{StruthDiss1999, AUTHOR = {Struth, Georg}, TITLE = {Canonical Transformation in Algebra, Universal Algebra and Logic}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, YEAR = {1998}, } @INCOLLECTION{Stuber1998AutDed, AUTHOR = {Stuber, J{\"u}rgen}, EDITOR = {Bibel, Wolfgang and Schmitt, Peter H.}, TITLE = {Superposition theorem proving for commutative rings}, BOOKTITLE = {Automated Deduction - A Basis for Applications. Volume III. Applications}, CHAPTER = {2}, ADDRESS = {Dordrecht, The Netherlands}, PUBLISHER = {Kluwer}, MONTH = {January}, SERIES = {Applied Logic Series}, VOLUME = {10}, YEAR = {1998}, PAGES = {31--55}, } @ARTICLE{Stuber1998TCS, AUTHOR = {Stuber, J{\"u}rgen}, JOURNAL = {Theoretical Computer Science}, TITLE = {Superposition theorem proving for abelian groups represented as integer modules}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {1/2}, PUBLISHER = {Elsevier}, MONTH = {November}, VOLUME = {208}, ISBN = {0304-3975}, YEAR = {1998}, PAGES = {149--177}, ABSTRACT = { We define a refutationally complete superposition calculus specialized for abelian groups represented as integer modules. Compared to a standard superposition prover which applies the axioms directly our calculus substantially reduces the number of inferences. We also investigate situations where the axioms give rise to variable overlaps and we develop techniques to avoid these explosive cases.}, } @PHDTHESIS{Stuber1999, AUTHOR = {Stuber, J{\"u}rgen}, TITLE = {Superposition Theorem Proving for Commutative Algebraic Theories}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {December}, YEAR = {1999}, ABSTRACT = {We develop special superposition calculi for first-order theorem proving in the theories of abelian groups, commutative rings, and modules and commutative algebras over fields or over the ring of integers, in order to make automated theorem proving in these theories more effective. The calculi are refutationally complete on arbitrary sets of ground clauses, which in particular may contain additional function symbols. The calculi are derived systematically from a representation of the theory as a convergent term rewriting system. Compared to standard superposition they have stronger ordering restrictions so that inferences are applied only to maximal summands, and they contain macro inference rules that use theory axioms in a goal directed fashion. In general we need additional inferences to handle critical peaks between extended clauses. We show that these are not needed for abelian groups and modules, and that for commutative rings and commutative algebras one such inference suffices for any pair of ground clauses. To facilitate the construction of term orderings for such calculi we introduce theory path orderings.}, } @INPROCEEDINGS{Stuber1999RTA, AUTHOR = {Stuber, J{\"u}rgen}, EDITOR = {Narendran, Paliath and Rusinowitch, Michael}, TITLE = {Theory path orderings}, BOOKTITLE = {Proceedings of the 10th International Conference on Rewriting Techniques and Applications (RTA-99)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Trento, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1631}, YEAR = {1999}, PAGES = {148--162}, ABSTRACT = { We introduce the notion of a theory path ordering~(TPO), which simplifies the construction of term orderings for superposition theorem proving in algebraic theories. To achieve refutational completeness of such calculi we need total, $E$-compatible and $E$-antisymmetric simplification quasi-orderings. The construction of a TPO takes as its ingredients a status function for interpreted function symbols and a precedence that makes the interpreted function symbols minimal. The properties of the ordering then follow from related properties of the status function. Theory path orderings generalize associative path orderings.}, } @INPROCEEDINGS{Stuber2000RTA, AUTHOR = {Stuber, J{\"u}rgen}, EDITOR = {Bachmair, Leo}, TITLE = {Deriving Theory Superposition Calculi from Convergent Term Rewriting Systems}, BOOKTITLE = {Proceedings of the 11th International Conference Rewriting Techniques and Applications (RTA-00)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Norwich, UK}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1833}, YEAR = {2000}, PAGES = {229--245}, } @MASTERSTHESIS{Stuber91, AUTHOR = {Stuber, J{\"u}rgen}, TITLE = {Inductive Theorem Proving for {H}orn Clauses}, SCHOOL = {Universit{\"a}t Dortmund}, TYPE = {Master's thesis}, YEAR = {1991}, ABSTRACT = {We show how to prove inductive consequences of horn clause specifications by horn clause completion. Most often one is interested in properties of the initial algebra. These stem from the facts that (a) it is generated by ground terms, and that (b) only provable ground equations are valid in the initial algebra. (a) is the basis of proofs by structural induction. (b) becomes relevant in the case of horn clauses, since the validity of a horn clause may depend on the fact that the conditions do not become true too often. We show that (a) is true for term generated algebras, whereas (b) is true for free algebras. Sophisticated completion procedures for horn clauses already carry out inductive proofs of type (b), in order to avoid orienting rules whose conditions are false in the resulting conditional rewrite system. To apply this to properties of type (a), we transform the specification, expressing the fact that a term t is ground as the provability of an atom gnd(t). By choosing a suitable selection strategy, we obtain proof procedures for the initial model, the class of all term generated models and the class of all free models. Additionally, it is possible to prove sufficient completeness of a specification. All our proof procedures are refutationally complete and linear.}, } @INPROCEEDINGS{StuberFTP97, AUTHOR = {Stuber, J{\"u}rgen}, EDITOR = {Bonacina, Maria Paola and Furbach, Ulrich}, TITLE = {Strong Symmetrization, Semi-Compatibility of Normalized Rewriting and First-Order Theorem Proving}, BOOKTITLE = {Proceedings of the International Workshop on First-Order Theorem Proving (FTP-97)}, PADDRESS = {Linz, Austria}, ADDRESS = {Schloss Hagenberg by Linz, Austria}, PUBLISHER = {Johannes Kepler Universit{\"a}t}, SERIES = {RISC-Linz Report}, VOLUME = {97-50}, YEAR = {1997}, PAGES = {125--129}, } @INPROCEEDINGS{StuberICLP94, AUTHOR = {Stuber, J{\"u}rgen}, EDITOR = {Van Hentenryck, Pascal}, TITLE = {Computing Stable Models by Program Transformation}, BOOKTITLE = {Proceedings of the 11th International Conference on Logic Programming (ICLP'94)}, PADDRESS = {Cambridge, USA}, ADDRESS = {Santa Margherita Ligure, Italy}, PUBLISHER = {MIT Press}, YEAR = {1994}, PAGES = {58--73}, ABSTRACT = {In analogy to the Davis-Putnam procedure we develop a new procedure for computing stable models of propositional normal disjunctive logic programs, using case analysis and simplification. Our procedure enumerates all stable models without repetition and without the need for a minimality check. Since it is not necessary to store the set of stable models explicitly, the procedure runs in polynomial space. We allow clauses with empty heads, in order to represent truth or falsity of a proposition as a one-literal clause. In particular, a clause of form $\mathop\sim A\rightarrow$ expresses that~$A$ is constrained to be true, without providing a justification for~$A$. Adding this clause to a program restricts its stable models to those containing~$A$, without introducing new stable models. Together with $A\rightarrow$ this provides the basis for case analysis. We present our procedure as a set of rules which transform a program into a set of solved forms, which resembles the standard method for presenting unification algorithms. Rules are sound in the sense that they preserve the set of stable models. A subset of the rules is shown to be complete in the sense that for each stable model a solved form can be obtained. The method allows for concise presentation, flexible choice of a control strategy and simple correctness proofs."}, } @INPROCEEDINGS{StuberRTA96, AUTHOR = {Stuber, J{\"u}rgen}, EDITOR = {Ganzinger, Harald}, TITLE = {Superposition Theorem Proving for Abelian Groups Represented as Integer Modules}, BOOKTITLE = {Rewriting Techniques and Applications, 7th International Conference, RTA-96}, PADDRESS = {Berlin, Germany}, ADDRESS = {New Brunswick, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1103}, ISBN = {3-540-61464-8}, YEAR = {1996}, PAGES = {33--47}, ABSTRACT = {We define a superposition calculus specialized for abelian groups represented as integer modules, and show its refutational completeness. This allows to substantially reduce the number of inferences compared to a standard superposition prover which applies the axioms directly. Specifically, equational literals are simplified, so that only the maximal term of the sums is on the left-hand side. Only certain minimal superpositions need to be considered; other superpositions which a standard prover would consider become redundant. This not only reduces the number of inferences, but also reduces the size of the AC-unification problems which are generated. That is, AC-unification is not necessary at the top of a term, only below some non-AC-symbol. Further, we consider situations where the axioms give rise to variable overlaps and develop techniques to avoid these explosive cases where possible.}, } @MASTERSTHESIS{Suchanek:DA:2005, AUTHOR = {Suchanek, Fabian M.}, TITLE = {Ontological Reasoning for Natural Language Understanding}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, YEAR = {2005}, } @INPROCEEDINGS{Talbot2000c, AUTHOR = {Talbot, Jean-Marc}, EDITOR = {Parigot, Michel and Voronkov, Andrei}, TITLE = {On the Alternation-free {H}orn mu-calculus}, BOOKTITLE = {Proceedings of the 7th International Conference on Logic for Programming and Automated Reasoning (LPAR-2000)}, PADDRESS = {Berlin, Germany}, ADDRESS = {La Reunion, France}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1955}, YEAR = {2000}, PAGES = {418--435}, } @ARTICLE{TalbotDevienneTison_Constraints2000, AUTHOR = {Talbot, Jean-Marc and Devienne, Philippe and Tison, Sophie}, JOURNAL = {Constraints}, TITLE = {Generalized Definite Set Constraints}, ADDRESS = {Dordrecht, the Netherlands}, NUMBER = {1/2}, PUBLISHER = {Kluwer}, MONTH = {January}, VOLUME = {5}, ISBN = {1383-7133}, YEAR = {2000}, PAGES = {161--202}, } @ARTICLE{TalbotIPL2000, AUTHOR = {Talbot, Jean-Marc}, JOURNAL = {Information Processing Letters}, TITLE = {The $\exists \forall^2$ fragment of the First-Order Theory of Set Constraints is $\pi^0_1$-hard}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {1/2}, PUBLISHER = {Elsevier}, VOLUME = {74}, ISBN = {0020-0190}, YEAR = {2000}, PAGES = {27--33}, } @INPROCEEDINGS{ThiebauxEtal2003, AUTHOR = {Thiebaux, Sylvie and Hoffmann, J{\"o}rg and Nebel, Bernhard}, EDITOR = {Gottlob, Georg}, TITLE = {In Defense of {PDDL} Axioms}, BOOKTITLE = {18th International Joint Conference on Artificial Intelligence}, PADDRESS = {San Francisco, USA}, ADDRESS = {Acapulco, Mexico}, PUBLISHER = {Morgan Kaufmann}, MONTH = {August}, YEAR = {2003}, PAGES = {961--966}, } @ARTICLE{ThiebauxEtal2005, AUTHOR = {Hoffmann, J{\"o}rg}, JOURNAL = {Artificial Intelligence}, TITLE = {In Defense of PDDL Axioms}, ADDRESS = {Amsterdam, The Netherlands}, NUMBER = {1-2}, PUBLISHER = {Elsevier}, VOLUME = {168}, ISBN = {0004-3702}, YEAR = {2005}, PAGES = {38--69}, } @MASTERSTHESIS{Timm97, AUTHOR = {Timm, Jan-Georg}, TITLE = {Testing the Satisfiability of RPO Constraints}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {October}, YEAR = {1997}, } @INPROCEEDINGS{Torre97b, AUTHOR = {van der Torre, Leendert W. N. and Tan, Yao-Hua}, TITLE = {Distinguishing different roles in normative reasoning}, BOOKTITLE = {Proceedings of the 6th International Conference on Artificial Intelligence and Law (ICAIL-97)}, ORGANIZATION = {The international association for artificial intelligence and law; the university of Melbourne law school}, PADDRESS = {New York, USA}, ADDRESS = {Melbourne, Australia}, PUBLISHER = {ACM}, ISBN = {0-89791-924-6}, YEAR = {1997}, PAGES = {225--232}, ABSTRACT = {In this paper we introduce the DIagnostic and DEcision-theoretic framework for DEontic reasoning diO(de)2. The framework diO(de)2 formalizes reasoning about violations and goals. We use this framework to discuss two theories of normative reasoning, diagnosis theory and (qualitative) decision theory. A crucial distinction between the two theories is their perspective on time. Diagnosis theory reasons about incomplete knowledge and only considers the past. It distinguishes between violations and non-violations. Qualitative decision theory reasons about decision variables and considers the future. It distinguishes between fulfilled obligations and unfulfilled obligations. Moreover, we discuss the relation between the two theories of normative reasoning and deontic logic. The theories formalize reasoning with norms, and they are thus different from deontic logic, that formalizes reasoning about norms. }, } @INPROCEEDINGS{Torre97c, AUTHOR = {van der Torre, Leendert W. N. and Tan, Yao-Hua}, EDITOR = {Brewka, Gerhard and Habel, Christopher and Nebel, Bernhard}, TITLE = {Reasoning about exceptions}, BOOKTITLE = {Proceedings of the 21st Annual German Conference on Artificial Intelligence (KI-97): Advances in Artificial Intelligence}, PADDRESS = {Berlin, Germany}, ADDRESS = {Freiburg}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1303}, ISBN = {3-540-63493-2}, YEAR = {1997}, PAGES = {405--408}, ABSTRACT = {In this paper we propose an exception logic - formalizing reasoning about exceptions. We use this logic to defend two claims. First, we argue that default logic - formalizing reasoning about default assumptions - is an extension of exception logic. A deconstruction argument shows that reasoning about exceptions is one of the first principles of reasoning about default assumptions. Second, we argue that two phases have to be distinguished in reasoning about exceptions, and therefore also in reasoning about default assumptions. We identify two causes of the distinction between two phases, the disjunction rule OR and right weakening RW. This sheds some new light on these `standard' (according to the Kraus-Lehmann-Magidor paradigm) properties of default inference. }, } @ARTICLE{Torre98.1, AUTHOR = {van der Torre, Leendert W. N. and Tan, Yao-Hua}, JOURNAL = {Journal of Artificial Intelligence and Law}, TITLE = {Diagnosis and Decision Making in Normative Reasoning}, VOLUME = {7}, YEAR = {1999}, PAGES = {51--67}, ABSTRACT = {Diagnosis theory reasons about incomplete knowledge and only considers the past. Itdistinguishes between violations and non-violations. Qualitative decision theory reasons aboutdecision variables and considers the future. It distinguishes between fulfilled goals and unfulfilledgoals. In this paper we formalize normative diagnoses and decisions in the special purposeformalism diOde2 as well as in extensions of the preference-based deontic logic 2dl. TheDIagnostic and DEcision-theoretic framework for DEontic reasoning diOde2 formalizesreasoning about violations and fulfillments, and is used to characterize the distinction betweennormative diagnosis theory and (qualitative) decision theory. The extension of thepreference-based deontic logic 2dl shows how normative diagnostic and decision-theoreticreasoning - i.e. reasoning about violations and fulfillments - can be formalized as an extension of deontic reasoning.}, } @INPROCEEDINGS{torre:aaai98, AUTHOR = {van der Torre, Leendert W. N. and Tan, Yao-Hua}, TITLE = {The temporal analysis of Chisholm's paradox}, BOOKTITLE = {Proceedings of the 15th National Conference, and 10th Conference on Innovative Applications of Artificial Intelligence (AAAI-98) and (IAAI-98)}, ORGANIZATION = {American Association for Artificial Intelligence (AAAI)}, PADDRESS = {Menlo Park, USA}, ADDRESS = {Madison, Wisconson}, PUBLISHER = {AAAI Press/ MIT Press}, ISBN = {0-262-51098-7}, YEAR = {1998}, PAGES = {650--655}, ABSTRACT = {Deontic logic, the logic of obligations and permissions, is plagued by several paradoxes that have to be understood before deontic logic can be used as a knowledge representation language. In this paper we extend the temporal analysis of Chisholm's paradox using a deontic logic that combines temporal and preferential notions. }, } @INCOLLECTION{torre:context99, AUTHOR = {van der Torre, Leendert W. N. and Tan, Yao-Hua}, EDITOR = {Cavalcanti, Marcos}, TITLE = {Contextual Deontic Logic: violation contexts and factual defeasibility}, BOOKTITLE = {Formal Aspects in Context}, ADDRESS = {Dordrecht, The Netherlands}, PUBLISHER = {Kluwer}, MONTH = {January}, SERIES = {Applied Logic Series}, YEAR = {1999}, PAGES = {173--192}, ABSTRACT = {In this article we introduce Contextual Deontic Logic (CDL) to analyze the relation between deontic, contextual and defeasible reasoning. The optimal state, and therefore the set of active obligations, can change radically when the violation context changes. In such cases we say that the obligations only in force in the previous violation context are defeated; contextual deontic logic is therefore a defeasible deontic logic. This is expressed by the definition OC(A|B) = O(A|B\-C): `A ought to be (done) if B is (done) in the context where C is (done)' is defined as `A ought to be (done) if B is (done) unless -C is (done).' The unless clause formalizes explicit exceptions and is analogous to the justification in Reiter's default rules. CDL is a monotonic defeasible deontic logic, because it has factual defeasibility but not overridden defeasibility. }, } @INPROCEEDINGS{torre:ecai98, AUTHOR = {van der Torre, Leendert W. N. and Tan, Yao-Hua}, EDITOR = {Prade, Henri}, TITLE = {An update semantics for prima facie obligations}, BOOKTITLE = {Proceedings of the 13th European Conference on Artificial Intelligence (ECAI-98)}, PADDRESS = {Chichester, USA}, ADDRESS = {Brighton, England}, PUBLISHER = {Wiley}, ISBN = {0-471-98431-0}, YEAR = {1998}, PAGES = {38--42}, ABSTRACT = {The deontic logic DUS is a Deontic Update Semantics for prescriptive obligations based on the update semantics of Veltman. In DUS the definition of logical validity of obligations is not based on static truth values but on dynamic action transitions. In this paper prescriptive prima facie obligations are formalized in update semantics. The logic formalizes the specificity principle, has reinstatement and does not have an irrelevance problem. Moreover, it handles the diagnostic problem by distinguishing between overridden, conflict and factual defeasibility. }, } @INPROCEEDINGS{torre:ecai98a, AUTHOR = {van der Torre, Leendert W. N.}, EDITOR = {Prade, Henri}, TITLE = {Labeled logics of conditional goals}, BOOKTITLE = {Proceedings of the 13th European Conference on Artificial Intelligence (ECAI-98)}, PADDRESS = {Chichester, USA}, ADDRESS = {Brighton, England}, PUBLISHER = {Wiley}, YEAR = {1998}, PAGES = {368--369}, ABSTRACT = {In this paper we introduce labeled logics of conditional goals. The logics have two remarkable properties. First, conflicting goals are consistent, because they can refer to different objectives. Second, a priori problematic combinations - e.g. strengthening of the antecedent and weakening of the consequent - are supported thanks to the labels. They are used to construct complex inductive definitions with several arguments. In the labeled logics we discuss transitivity, formalizing that conditional goals can be applied one after the other, and the disjunction rule, formalizing reasoning by cases. }, } @INPROCEEDINGS{torre:ecsqaru99, AUTHOR = {van der Torre, Leendert W. N.}, EDITOR = {Hunter, Anthony and Parsons, Simon}, TITLE = {Defeasible Goals}, BOOKTITLE = {Proceedings of the 5th European Conference on Symbolic and Quantitative Approaches to Reasoning and Uncertainty (ECSQARU-99)}, PADDRESS = {Berlin, Germany}, ADDRESS = {London}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1638}, ISBN = {3-540-66131-X}, YEAR = {1999}, PAGES = {374--385}, ABSTRACT = {In this paper we study defeasible goals in Gabbay's labelled deductive systems. We prove the completeness of a simple and elegant proof theory for the labelled logic of defeasible goals by proving two phasing theorems. }, } @INPROCEEDINGS{torre:ijcai99, AUTHOR = {van der Torre, Leendert W. N. and Tan, Yao-Hua}, TITLE = {Rights, Duties and Commitments Between Agents}, BOOKTITLE = {Proceedings of the 16th International Joint Conference on Artificial Intelligence (IJCAI-99)}, ORGANIZATION = {IJCAII and the Scandinavian AI Societies}, PADDRESS = {San Francisco, USA}, ADDRESS = {Stockholm, Sweden}, PUBLISHER = {Morgan Kaufmann}, VOLUME = {2}, ISBN = {1-55860-613-0}, YEAR = {1999}, PAGES = {1239--1244}, ABSTRACT = {In this paper we introduce a multi agent deontic update semantics, that builds on a logic of prescriptive obligations (norms) and a logic of descriptive obligations (normative propositions). In this preference-based logic we formalize rights as a new type of strong prescriptive permissions and duties and commitments as prescriptive obligations between agents. }, } @INPROCEEDINGS{torre:jelia98, AUTHOR = {van der Torre, Leendert W. N.}, EDITOR = {Dix, J{\"u}rgen and Fariñas del Cerro, Lu{\'i}s and Furbach, Ulrich}, TITLE = {Phased labeled logics of conditional goals}, BOOKTITLE = {Proceedings of the 6th European Workshop on Logics in AI: Logics in Artificial Intelligence (JELIA-98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Schloss Dagstuhl}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1489}, YEAR = {1998}, PAGES = {92--106}, ABSTRACT = {In this paper we introduce phased labeled logics of conditional goals. Labels are used to impose restrictions on the proof theory of the logic. The restriction discussed in this paper is that a proof rule can be blocked in a derivation due to the fact that another proof rule has been applied earlier in the derivation. We call a set of proof rules that can be applied in any order a phase in the proof theory. We propose a one-phase logic of goals containing four proof rules, and we show that it is equivalent to a four-phase logic of goals in which each phase contains exactly one proof rule. The proof theory of the four-phase logic of goals is much more efficient, because other orderings no longer have to be considered. }, } @INPROCEEDINGS{torre:jelia98a, AUTHOR = {van der Torre, Leendert W. N. and Tan, Yao-Hua}, EDITOR = {Dix, J{\"u}rgen and Fariñas del Cerro, Lu{\'i}s and Furbach, Ulrich}, TITLE = {Prohairetic Deontic Logic (PDL)}, BOOKTITLE = {Proceedings of the 6th European Workshop on Logics in AI: Logics in Artificial Intelligence (JELIA-98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Schloss Dagstuhl}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1489}, YEAR = {1998}, PAGES = {77--91}, ABSTRACT = {In this paper we introduce Prohairetic Deontic Logic, a preference-based dyadic deontic logic.An obligation `A should be (done) if B is (done)' is true if (1) no $\neg$ A/\B is preferred to anA/\B and (2) the preferred B are A. We show that this mixed representation solves severalproblems of deontic logic. Moreover, we discuss the relation between preference-based deonticlogic and qualitative decision theory. }, } @ARTICLE{torre:jmai99, AUTHOR = {van der Torre, Leendert W. N. and Tan, Yao-Hua}, JOURNAL = {Annals of Mathematics and Artificial Intelligence}, TITLE = {Contrary-to-duty reasoning with preference-based dyadic obligations}, ADDRESS = {?}, PUBLISHER = {Baltzer}, MONTH = {January}, VOLUME = {27}, YEAR = {1999}, PAGES = {49--78}, } @INPROCEEDINGS{torre:uai99, AUTHOR = {van der Torre, Leendert W. N. and Tan, Yao-Hua}, EDITOR = {Laskey, Kathryn B. and Prade, Henri}, TITLE = {An Update Semantics for Defeasible Obligations}, BOOKTITLE = {Proceedings of the 15th Conference on Uncertainty in Artificial Intelligence (UAI-99)}, ORGANIZATION = {Association for Uncertainty in AI (AUAI)}, PADDRESS = {San Francisco, USA}, ADDRESS = {Stockholm, Sweden}, PUBLISHER = {Morgan Kaufmann}, ISBN = {1-55860-614-9}, YEAR = {1999}, PAGES = {631--638}, } @INCOLLECTION{torre:update99, AUTHOR = {van der Torre, Leendert W. N. and Tan, Yao-Hua}, EDITOR = {McNamara, Paul and Prakken, Henri}, TITLE = {An update semantics for deontic reasoning}, BOOKTITLE = {Norms, Logics and Information Systems: New Studies on Deontic Logic and Computer Science}, ADDRESS = {Amsterdam, the Netherlands}, PUBLISHER = {IOS Press}, MONTH = {January}, SERIES = {Frontiers in Artificial Intelligence and Applications}, VOLUME = {49}, ISBN = {ISSN: 0922-6389}, YEAR = {1999}, PAGES = {73--90}, ABSTRACT = {In this paper we propose the deontic logic DUS, that formalizes reasoning about prescriptive obligations in update semantics. In DUS the definition of logical validity of obligations is not based on truth values but on action dynamics. You know the meaning of a normative sentence if you know the change it brings about in the ideality relation of anyone the news conveyed by the norm applies to. }, } @INPROCEEDINGS{TruegEtal2004, AUTHOR = {Trueg, Sebastian and Hoffmann, J{\"o}rg and Nebel, Bernhard}, EDITOR = {Biundo, Susanne and Fr{\"u}hwirth, Thom and Palm, G{\"u}nther}, TITLE = {Applying Automatic Planning Systems to Airport Ground Traffic Control -- A Feasibility Study}, BOOKTITLE = {KI 2004: Advances in Artificial Intelligence: 27th Annual German Conference on AI, KI 2004}, PADDRESS = {Berlin, Germany}, ADDRESS = {Ulm, Germany}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {3238}, ISBN = {3-540-23166-8}, YEAR = {2004}, PAGES = {183--197}, } @PHDTHESIS{Tzakova1999, AUTHOR = {Tzakova, Miroslava}, TITLE = {Hybrid Languages}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, YEAR = {1999}, } @INPROCEEDINGS{Tzakova98a, AUTHOR = {Blackburn, Patrick and Tzakova, Miroslava}, EDITOR = {Boros, Endre and Greiner, Russel}, TITLE = {A Hybrid Concept Language}, BOOKTITLE = {Proceedings of the 5th International Symposium on Artificial Intelligence and Mathematics}, PADDRESS = {Rutgers University, USA}, ADDRESS = {Fort Lauderdale, Florida}, PUBLISHER = {http://rutcor.rutgers.edu/~amai}, YEAR = {1998}, ABSTRACT = {We introduce a concept language for representing knowledge. Relying on the well-known correspondence between the description logic ${\cal ALC}$ and the multi-modal logic $K_{(m)}$, we define a {\em hybrid language\/} that is an extension of $K_{(m)}$. The language (in addition to the propositional variables and modal operators) contains variables across individuals and a quantifier that binds them. Combining features of modal and first-order logic, our formalism increases the expressivity of $\cal{ALC}$ in a natural and uniform way. In particular, it can define number restrictions, collections of individuals and membership assertions. In fact, the hybrid language is a general formalism in which a variety of descriptive concepts as well as TBox- and ABox-statements can be formulated in a natural way. We present an axiomatisation and prove its completeness by using so-called {\it witnessed} models as a bridge between modal and first-order completeness techniques.}, } @ARTICLE{Tzakova98b, AUTHOR = {Blackburn, Patrick and Tzakova, Miroslava}, JOURNAL = {Logic Journal of the IGPL}, TITLE = {Hybrid Completeness}, NUMBER = {4}, PUBLISHER = {Oxford University Press}, MONTH = {July}, VOLUME = {6}, ISBN = {1368-9894}, YEAR = {1998}, PAGES = {625--650}, NOTE = {Revised Version of MPI-I-97-2-007}, ABSTRACT = {In this paper we discuss two {\em hybrid languages\/}, ${\cal L}(\forall)$ and ${\cal L}(\downarrow)$, and provide them with complete axiomatizations. Both languages combine features of modal and classical logic. Like modal languages, they contain modal operators and have a Kripke semantics. Unlike modal languages, in these systems it is possible to `label' states by using $\forall$ and $\downarrow$ to bind special {\em state variables\/}. This paper explores the consequences of hybridization for completeness. As we shall show, the challenge is to blend the modal idea of {\em canonical models\/} with the classical idea of {\em witnessed\/} maximal consistent sets. The languages ${\cal L}(\forall)$ and ${\cal L}(\downarrow)$ provide us with two extreme examples of the issues involved. In the case of ${\cal L}(\forall)$, we can combine these ideas relatively straightforwardly with the aid of analogs of the {\em Barcan\/} axioms coupled with a {\em modal theory of labeling\/}. In the case of ${\cal L}(\downarrow)$, on the other hand, although we can still formulate a theory of labeling, the Barcan analogs are not valid. We show how to overcome this difficulty by using $\mbox{{\it COV}}^{ \ \ast}$, an infinite collection of additional rules of proof which has been used in a number of investigations of extended modal logic.}, } @ARTICLE{Tzakova98c, AUTHOR = {Blackburn, Patrick and Tzakova, Miroslava}, JOURNAL = {Annals of Mathematics and Artificial Intelligence}, TITLE = {Hybridizing Concept Languages}, NUMBER = {1/4}, PUBLISHER = {Baltzer}, VOLUME = {24}, ISBN = {1012-2443}, YEAR = {1998}, PAGES = {23--49}, ABSTRACT = {This paper shows how to increase the expressivity of concept languages using a strategy called {\em hybridization}. Building on the well-known correspondences between modal and description logics, two {\em hybrid languages\/} are defined. These languages are called `hybrid' because, as well as the familiar propositional variables and modal operators, they also contain {\em variables across individuals\/} and a binder that {\em binds\/} these variables. As is shown, combining aspects of modal and first-order logic in this manner allows the expressivity of concept languages to be boosted in a natural way, making it possible to define number restrictions, collections of individuals, irreflexivity of roles, and TBox- and ABox-statements. Subsequent addition of the {\em universal modality\/} allows the notion of subsumption to be internalized, and enables the representation of queries to arbitrary first-order knowledge bases. The paper notes themes shared by the hybrid and concept language literatures, and draws attention to a little-known body of work by the late Arthur Prior.}, } @TECHREPORT{Tzakova98d, AUTHOR = {Blackburn, Patrick and Tzakova, Miroslava}, TITLE = {Hybrid Languages and Temporal Logic (Full Version)}, INSTITUTION = {Computational Lingustics, Universit{\"a}t des Saarlandes}, TYPE = {Research Report}, ADDRESS = {Saarbr{\"u}cken, Germany}, NUMBER = {CLAUS 96}, MONTH = {July}, YEAR = {1998}, PAGES = {50}, ABSTRACT = {Hybridization is a method invented by Arthur Prior for extending the expressive power of modal languages. Although developed in interesting ways by Robert Bull, and the Sofia school (notably, George Gargov, Valentin Goranko, Solomon Passy and Tinko Tinchev), the method remains little known. In our view this has deprived temporal logic of a valuable tool. The aim of the paper is to explain why hybridization is useful in temporal logic. We make two major points, the first technical, the second conceptual. Technically, we show that hybridization gives rise to well-behaved logics that exhibit an interesting synergy between modal and classical ideas. This synergy, obvious for hybrid languages with full first-order expressive strength, is demonstrated for three weaker local languages, all of which are capable of defining the Until operator; we provide simple minimal axiomatizations for all three systems, and show that in a wide range of temporally interesting cases, extended completeness results can be obtained automatically. Conceptually, we argue that the idea of sorted atomic symbols which underpins the hybrid enterprise can be developed much further. To illustrate this, we discuss the advantages and disadvantages of a simple hybrid language which can quantify over paths. This is the original version of a paper which was accepted for publication in a special issue of the Journal of the IGPL on temporal logic. Unfortunately, the length of the article meant that it had to be drastically cut, and only a shorter version will appear. While the short version covers one of the most elegant results (@-driven completeness results) and is slightly more up to date in certain respects, the long version is probably the most detailed discussion of the completeness theory of local hybrid languages around. The long version also contains many lengthy footnotes. These outline the history of hybrid languages in considerable detail, and contain many remarks on philosophical, methodological, and technical issues. }, } @ARTICLE{Tzakova99a, AUTHOR = {Blackburn, Patrick and Tzakova, Miroslava}, JOURNAL = {Logic Journal of the IGPL}, TITLE = {Hybrid Languages and Temporal Logic}, NUMBER = {1}, PUBLISHER = {Oxford University Press}, MONTH = {January}, VOLUME = {7}, ISBN = {1368-9894}, YEAR = {1999}, PAGES = {27--54}, NOTE = {Revised Version of MPI-I-98-2-006. }, ABSTRACT = {Hybridization is a method invented by Arthur Prior for extending the expressive power of modal languages. Although developed in interesting ways by Robert Bull, and by the Sofia school (notably, George Gargov, Valentin Goranko, Solomon Passy and Tinko Tinchev), the method remains little known. In our view this has deprived temporal logic of a valuable tool. The aim of the paper is to explain why hybridization is useful in temporal logic. We make two major points, the first technical, the second conceptual. First, we show that hybridization gives rise to well-behaved logics that exhibit an interesting synergy between modal and classical ideas. This synergy, obvious for hybrid languages with full first-order expressive strength, is demonstrated for a weaker local language capable of defining the {\it Until\/} operator; we provide a minimal axiomatization, and show that in a wide range of temporally interesting cases extended completeness results can be obtained automatically. Second, we argue that the idea of sorted atomic symbols which underpins the hybrid enterprise can be developed further. To illustrate this, we discuss the advantages and disadvantages of a simple hybrid language which can quantify over paths.}, } @INPROCEEDINGS{Tzakova99b, AUTHOR = {Tzakova, Miroslava}, EDITOR = {Murray, Neil V.}, TITLE = {Tableau Calculi for Hybrid Logics}, BOOKTITLE = {Proceedings of the International Conference TABLEAUX'99 - Automated Reasoning with Analytic Tableaux and Related Methods}, PADDRESS = {Berlin, Germany}, ADDRESS = {Saratoga Springs, NY, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1617}, ISBN = {3-540-66086-0}, YEAR = {1999}, PAGES = {278--292}, ABSTRACT = {Hybrid logics were proposed as a way of boosting the expressivity of modal logics via a novel mechanism: adding labels for states in Kripke models and viewing these labels as formulae. In addition, hybrid logics may contain quantifiers to bind the labels. Thus, hybrid logics have both Kripke semantics and a first-order binding apparatus. We present prefixed tableau calculi for weak hybrid logics (proper fragments of classical logic) as well as for hybrid logics having full first-order expressive power, and give a general method for proving completeness. For the weak quantifier-free logics we present a tableau-based decision procedure.}, } @INPROCEEDINGS{Veanes98, AUTHOR = {Veanes, Margus}, EDITOR = {Pratt, Vaughan}, TITLE = {The Relation Between Second-Order Unification and Simultaneous Rigid {E}-Unification}, BOOKTITLE = {Proceedings of the 13th Annual IEEE Symposium on Logic in Computer Science (LICS-98)}, ORGANIZATION = {IEEE Computer Society Technical Committee on Mathematical Foundations of Computing}, PADDRESS = {Los Alamitos, USA}, ADDRESS = {Indianapolis, Indiana}, PUBLISHER = {IEEE}, ISBN = {0-8186-8506-9/1043-6871}, YEAR = {1998}, PAGES = {264--275}, ABSTRACT = {Simultaneous rigid $E$-unification, or SREU for short, is a fundamental problem that arises in global methods of automated theorem proving in classical logic with equality. In order to do proof search in intuitionistic logic with equality one has to handle SREU as well. Furthermore, restricted forms of SREU are strongly related to word equations and finite tree automata. It was recently shown that second-order unification has a very natural reduction to simultaneous rigid $E$-unification, which constituted probably the most transparent undecidability proof of SREU. Here we show that there is also a natural encoding of SREU in second-order unification. It follows that the problems are logspace equivalent. So second-order unification plays the same fundamental role as SREU in automated reasoning in logic with equality. We exploit this connection and use finite tree automata techniques to present a very elementary undecidability proof of second-order unification, by reduction from the halting problem for Turing machines. It follows from that proof that second-order unification is undecidable for all nonmonadic second-order term languages having at least two second-order variables with sufficiently high arities.}, } @ARTICLE{Veanes99, AUTHOR = {Veanes, Margus}, JOURNAL = {Information Processing Letters}, TITLE = {Farmer's Theorem Revisited}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {1/2}, PUBLISHER = {Elsevier}, MONTH = {April}, VOLUME = {74}, ISBN = {0020-0190}, YEAR = {2000}, PAGES = {47--53}, ABSTRACT = {The main result is that there is an integer $n$, such that second-order unification is undecidable in all non-monadic second-order term languages with at least $n$ \emph{first-order} variables, and even if the arguments of all second-order variables are ground terms of size bounded by $n$ and the total number of variable occurrences is at most $n$.}, } @MASTERSTHESIS{Veit1999, AUTHOR = {Veit, J{\"o}rg}, TITLE = {Formal Fairness Proofs for Optimistic Contract Signing Protocols}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, MONTH = {October}, YEAR = {1999}, } @PHDTHESIS{Vigano97, AUTHOR = {Vigan{\`o}, Luca}, TITLE = {A Framework for Non-Classical Logics}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, YEAR = {1997}, ABSTRACT = {The subject of this work is the development and investigation of a \emph{framework} for the modular and uniform representation and implementation of \emph{non-classical logics}, in particular modal and relevance logics. Logics are presented as labelled natural deduction (or sequent) systems, which are proved to be sound and complete with respect to the corresponding Kripke-style semantics. We investigate the proof theory of our systems, and show them to possess structural properties such as normalization and the subformula property, which we exploit to establish not only general advantages and limitations of our approach with respect to related ones, but also, by means of a substructural analysis, decidability and complexity results for (some of) the logics we consider. All of our proof systems have been implemented in the generic theorem prover Isabelle, thus providing a simple and natural environment for interactive proof development. }, } @INPROCEEDINGS{Vorobyov1998CSL, AUTHOR = {Vorobyov, Sergei}, EDITOR = {Gottlob, Georg and Grandjean, Etienne and Seyr, Katrin}, TITLE = {Subtyping Functional+Nonempty Record Types}, BOOKTITLE = {Proceedings of the 12th International Workshop on Computer Science Logic (CSL-98), Annual Conference on the EACSL}, ORGANIZATION = {European Association for Computer Science Logic}, PADDRESS = {Berlin, Germany}, ADDRESS = {Brno, Czech Republic}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1584}, ISBN = {3-540-65922-6}, YEAR = {1999}, PAGES = {285--297}, ABSTRACT = {\begin{abstract} \emph{Solving systems of subtype constraints} (or \emph{subtype inequalities}) is in the core of efficient \emph{type reconstruction} in modern object-oriented languages with subtyping and inheritance, two problems known \emph{polynomial time equivalent}. It is important to know how different combinations of type constructors influence the complexity of the problem. We show the \emph{NP-hardness} of the satisfiability problem for subtype inequalities between object types built by using simultaneously both the functional and the non-empty record type constructors, but without any atomic types and atomic subtyping. The class of constraints we address is intermediate with respect to known classes. For pure functional types with atomic subtyping of a special non-lattice (\emph{crown}) form solving subtype constraints is PSPACE-complete \cite{Tiuryn92,Frey97}. On the other hand, if there are no atomic types and subtyping on them, but the largest $\top$ type is included, then both pure functional and pure record (separately) subtype constraints are \emph{polynomial time solvable} \cite{KozenPalsbergSchwartzbach94,Palsberg95ic}, which is mainly due to the lattice type structure. We show that combining the functional and nonempty record constructors yields NP-hardness \emph{without any atomic subtyping}, and the same is true for just a single type constant with a nonempty record constructor. \end{abstract}}, } @INPROCEEDINGS{Vorobyov1998MFCS, AUTHOR = {Vorobyov, Sergei}, EDITOR = {Brim, Lubos and Gruska, Jozef and Zlatuska, Jir{\'i}}, TITLE = {$\forall\exists^\ast$-Equational Theory of Context Unification is ${\Pi}_1^0$-Hard}, BOOKTITLE = {Proceedings of the 23rd International Symposium on Mathematical Foundations of Computer Science (MFCS-98)}, ORGANIZATION = {Mazaryk University, European Assoc of Computer Science Logic}, PADDRESS = {Berlin, Germany}, ADDRESS = {Brno, Czech Republic}, PUBLISHER = {Springer}, MONTH = {August}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1450}, ISBN = {3-540-64827-5}, YEAR = {1998}, PAGES = {597--606}, ABSTRACT = {\begin{abstract} Context unification is a particular case of second-order unification, where all second-order variables are \emph{unary} and only \emph{linear} functions are sought for as solutions. Its decidability is an open problem. We present the simplest (currently known) undecidable quantified fragment of the theory of \emph{context unification} by showing that for every signature containing a $\geq\!2$-ary symbol one can construct a \emph{context equation} ${\mathcal E}\,(p,r,\overline{F},\overline{w})$ with parameter $p$, first-order variables $r$, $\overline{w}$, and context variables $\overline{F}$ such that the set of true sentences of the form \[\forall r\;\exists\;\overline{F}\;\exists\;\overline{w}\;\; {\mathcal E}(p,r,\overline{F},\overline{w})\] is $\Pi_1^0$-hard (i.e., every co-r.e. set is many-one reducible to it), as $p$ ranges over finite words of a binary alphabet. Moreover, the existential prefix above contains just 5 context and 3 first-order variables. \end{abstract}}, } @ARTICLE{Vorobyov2000-aecu, AUTHOR = {Vorobyov, Sergei}, JOURNAL = {Theoretical Computer Science}, TITLE = {$\forall\exists^5$-equational theory of context unification is undecidable}, ADDRESS = {Amsterdam, the Netherlands}, PUBLISHER = {Elsevier}, VOLUME = {275}, YEAR = {2002}, PAGES = {463--479}, } @ARTICLE{Vorobyov2000-OSR, AUTHOR = {Vorobyov, Sergei}, JOURNAL = {Information and Computation}, TITLE = {The undecidability of the first-order theories of one step rewriting in linear canonical systems}, ADDRESS = {San Diego, USA}, PUBLISHER = {Academic Press}, VOLUME = {175}, YEAR = {2002}, PAGES = {182--213}, } @INPROCEEDINGS{Vorobyov94b, AUTHOR = {Vorobyov, Sergei}, TITLE = {Fsub with recursive types: `Types-As-Propositions´ Interpretations in M. Rabin's S2S}, BOOKTITLE = {Proceedings of JFLA'95: Journ{\'e}es Francophones des Langages Applicatifs (JFLA'95)}, PADDRESS = {Rocquencourt, France}, ADDRESS = {Bois d'Amont, France}, PUBLISHER = {INRIA}, MONTH = {January}, YEAR = {1995}, PAGES = {49--73}, ABSTRACT = {Subtyping judgments of the polymorphic second-order typed lambda-calculus Fsub extended by recursive types and different known inference rules for these types could be interpreted in S2S, M.Rabin's monadic second-order theory of two successor functions. On the one hand, this provides a comprehensible model of the parametric and inheritance polymorphisms over recursive types, on the other, proves that the corresponding subtyping theories are not essentially undecidable, i.e., possess consistent decidable extensions.}, } @INPROCEEDINGS{Vorobyov94h, AUTHOR = {Vorobyov, Sergei}, TITLE = {Structural decidable extensions of bounded quantification}, BOOKTITLE = {Proceedings of the 22nd ACM Symposium on Principles of Programming Languages (POPL'95)}, INSTITUTION = {Max-Planck-Institut f{\"u}r Informatik}, TYPE = {Technical Report}, PADDRESS = {New York, USA}, ADDRESS = {San Francisco, USA}, PUBLISHER = {ACM}, MONTH = {January}, YEAR = {1995}, PAGES = {164--175}, NOTE = {Also available as Research Report MPI-I-94-257, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken, Germany}, ABSTRACT = {We show how the subtype relation of the well-known system Fsub, the second-order polymorphic lambda-calculus with bounded universal type quantification and subtyping, due to Cardelli, Wegner, Bruce, Longo, Curien, Ghelli, proved undecidable by Pierce (POPL'92), can be interpreted in the (weak) monadic second-order theory of one (B\"uchi), two (Rabin), several, or infinitely many successor functions. These (W)SnS-interpretations show that the undecidable system Fsub possesses consistent decidable extensions, i.e., Fsub is not essentially undecidable (Tarski, 1949). \par We demonstrate an infinite class of structural decidable extensions of Fsub, which combine traditional subtype inference rules with the above (W)SnS-interpretations. All these extensions, which we call systems FsubSnS, are still more powerful than Fsub, but less coarse than the direct (W)SnS-interpretations. \par The main distinctive features of the systems FsubSnS are: 1) decidability, 2) closure w.r.t.\ transitivity; 3) structuredness, e.g., they never subtype a functional type to a universal one or vice versa, 4) they all contain the powerful rule for subtyping boundedly quantified types.}, } @INPROCEEDINGS{Vorobyov96ASIAN96, AUTHOR = {Vorobyov, Sergei}, EDITOR = {Jaffar, Joxan and Yap, Roland H. C.}, TITLE = {On the bounded theories of finite trees}, BOOKTITLE = {Second Asian Computing Science Conference, ASIAN'96}, TYPE = {Full paper}, PADDRESS = {Berlin, Germany}, ADDRESS = {Singapore}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1179}, ISBN = {3-540-62031-1}, YEAR = {1996}, PAGES = {152--161}, ABSTRACT = { The theory of finite trees is the full first-order theory of equality in the Herbrand universum (the set of ground terms) over a functional signature containing non-unary function symbols and constants. Albeit decidable, this theory turns out to be of non-elementary complexity [Vorobyov96CADE96]. To overcome the intractability of the theory of finite trees, we introduce in this paper the bounded theory of finite trees. This theory replaces the usual equality $=$, interpreted as identity, with the infinite family of approximate equalities ``down to a fixed given depth'' $\{=^d\}_{d\in\omega}$, with $d$ written in binary notation, and $s=^dt$ meaning that the ground terms $s$ and $t$ coincide if all their branches longer than $d$ are cut off. By using a refinement of Ferrante-Rackoff's complexity-tailored Ehrenfeucht-Fraisse games, we demonstrate that the bounded theory of finite trees can be decided within linear double exponential space $2^{2^{cn}}$ ($n$ is the length of input) for some constant $c>0$.}, } @INPROCEEDINGS{Vorobyov96CADE96, AUTHOR = {Vorobyov, Sergei}, EDITOR = {McRobbie, M. A. and Slaney, J. K.}, TITLE = {An improved lower bound for the elementary theories of trees}, BOOKTITLE = {Proceedings of the 13th International Conference on Automated Deduction (CADE-13)}, ORGANIZATION = {AT\&T, Bell Labs, Lucent, IEEE, CADE inc}, TYPE = {Full paper}, PADDRESS = {Berlin, Germany}, ADDRESS = {New Brunswick, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1104}, ISBN = {3-540-61-511-3}, YEAR = {1996}, PAGES = {275--287}, ABSTRACT = { The first-order theories of finite and rational, constructor and feature trees possess complete axiomatizations and are decidable by quantifier elimination [Malcev 61, Kunen 87, Maher 88, Comon-Lescanne 89, Hodges 93, Backofen-Smolka 92, Smolka-Treinen 92, Backofen-Treinen94, Backofen95]. By using the uniform inseparability lower bounds techniques due to [Compton-Henson 90], based on representing large binary relations by means of short formulas manipulating with high trees, we prove that all the above theories, as well as all their subtheories, are NON-ELEMENTARY in the sense of Kalmar, i.e., cannot be decided within time bounded by a $k$-story exponential function for any fixed $k$. Moreover, for some constant $d>0$ these decision problems require nondeterministic time exceeding $\exp_\infty(dn)$}, } @INPROCEEDINGS{Vorobyov97LICS97, AUTHOR = {Vorobyov, Sergei}, EDITOR = {Winskel, Glynn}, TITLE = {The `hardest´ natural decidable theory}, BOOKTITLE = {Proceedings of the Twelfth Annual IEEE Symposium on Logic in Computer Science (LICS-97)}, ORGANIZATION = {IEEE Computer Society}, TYPE = {Full paper}, PADDRESS = {New York, USA}, ADDRESS = {Warsaw, Poland}, PUBLISHER = {IEEE}, MONTH = {June-July}, ISBN = {0-8186-7925-5}, YEAR = {1997}, PAGES = {294--305}, ABSTRACT = {Since mid-seventies it was an open problem as to whether there exist natural decidable theories requiring time (lower bound) exceeding any linearly growing towers of 2s to decide. It was conjectured that all natural decidable theories can be decided (upper bound) within time bounded by a tower of 2s growing linearly with the length of input. Although it happens to be true for the majority of non-elementary theories (Rabin's S2S, theory of term algebras, extended regular expressions, etc), the conjecture fails. We demonstrate that a modest fragment of L.Henkin's theory of propositional types (1963) has the tower of 2s growing *exponentially* with the length of input as a lower bound. This new unprecedentedly high lower bound allows us to considerably improve the known lower bounds and to settle the new ones for other theories.}, } @INPROCEEDINGS{Vorobyov97RTA97, AUTHOR = {Vorobyov, Sergei}, EDITOR = {Comon, Hubert}, TITLE = {The first-order theory of one step rewriting in linear noetherian systems is undecidable}, BOOKTITLE = {Proceedings of the 8th International Conference on Rewriting Techniques and Applications (RTA-97)}, TYPE = {Full paper}, PADDRESS = {Berlin, Germany}, ADDRESS = {Sitges, Spain}, PUBLISHER = {Springer}, MONTH = {June}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1232}, ISBN = {3-540-62950-5}, YEAR = {1997}, PAGES = {254--268}, ABSTRACT = {We construct a finite linear finitely terminating rewrite rule system with undecidable theory of one step rewriting.}, } @INPROCEEDINGS{VorobyovVoronkov1998PODS, AUTHOR = {Vorobyov, Sergei and Voronkov, Andrei}, TITLE = {Complexity of Nonrecursive Logic Programs with Complex Values}, BOOKTITLE = {Proceedings of the 17th ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems (PODS-98)}, ORGANIZATION = {Asoc Comput Machinery, Boeing}, PADDRESS = {New York, USA}, ADDRESS = {Saeattle, Washington, U.S.A.}, PUBLISHER = {ACM}, MONTH = {June}, ISBN = {0-89791-996-3}, YEAR = {1998}, PAGES = {244--253}, ABSTRACT = { We investigate complexity of the $\success$ problem for logic query languages with complex values: check whether a query defines a nonempty set. The $\success$ problem for recursive query languages with complex values is undecidable, so we study the complexity of nonrecursive queries. By complex values we understand values such as trees, finite sets, and multisets. Due to the well-known correspondence between relational query languages and datalog, our results can be considered as results about relational query languages with complex values. The paper gives a complete complexity classification of the $\success$ problem for nonrecursive logic programs over trees depending on the underlying signature, presence of negation, and range restrictedness. We also prove several results about finite sets and multisets.}, } @ARTICLE{Voronkov99, AUTHOR = {Voronkov, Andrei}, JOURNAL = {The Journal of Symbolic Logic}, TITLE = {The ground-negative fragment of first-order logics is $\pi^p_2$-complete}, NUMBER = {3}, PUBLISHER = {Association for Symbolic Logic}, MONTH = {September}, VOLUME = {64}, YEAR = {1999}, PAGES = {984--990}, } @PHDTHESIS{Waldmann1997, AUTHOR = {Waldmann, Uwe}, TITLE = {Cancellative Abelian Monoids in Refutational Theorem Proving}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, MONTH = {July}, YEAR = {1997}, ABSTRACT = {We present a constraint superposition calculus in which the axioms of cancellative abelian monoids and, optionally, further axioms (e.g., torsion-freeness) are integrated. Cancellative abelian monoids comprise abelian groups, but also such ubiquitous structures as the natural numbers or multisets. Our calculus requires neither extended clauses nor explicit inferences with the theory axioms. The number of variable overlaps is significantly reduced by strong ordering restrictions and powerful variable elimination techniques; in divisible torsion-free abelian groups, variable overlaps can even be avoided completely. Thanks to the equivalence of torsion-free cancellative and totally ordered abelian monoids, our calculus allows us to solve equational problems in totally ordered abelian monoids without requiring a detour via ordering literals.}, } @INPROCEEDINGS{Waldmann1997FTP, AUTHOR = {Waldmann, Uwe}, EDITOR = {Bonacina, Maria Paola and Furbach, Ulrich}, TITLE = {A Superposition Calculus for Divisible Torsion-Free Abelian Groups}, BOOKTITLE = {Proceedings of the International Workshop on First-Order Theorem Proving (FTP-97)}, TYPE = {Extended Abstract}, PADDRESS = {Linz, Austria}, ADDRESS = {Linz, Austria}, NUMBER = {97-50}, PUBLISHER = {Johannes Kepler Universit{\"a}t}, SERIES = {RISC-Linz Report Series}, YEAR = {1997}, PAGES = {130--134}, ABSTRACT = {Variable overlaps are one of the main sources for the inefficiency of AC or ACU theorem proving calculi. In the presence of the axioms of abelian groups or at least cancellative abelian monoids, ordering restrictions allow us to avoid some of these overlaps, but inferences with unshielded variables remain necessary. In divisible torsion-free abelian groups, for instance the rational numbers, every clause can be transformed into an equivalent clause without unshielded variables. We show how such a variable elimination algorithm can be integrated into the cancellative superposition calculus. The resulting calculus is refutationally complete with respect to the axioms of divisible torsion-free abelian groups and allows us to dispense with variable overlaps altogether. If abstractions are performed eagerly, the calculus makes it furthermore possible to avoid the computation of AC unifiers and AC orderings.}, } @INPROCEEDINGS{Waldmann1998, AUTHOR = {Waldmann, Uwe}, EDITOR = {Kirchner, Claude and Kirchner, H{\'e}l{\`e}ne}, TITLE = {Superposition for Divisible Torsion-Free Abelian Groups}, BOOKTITLE = {Proceedings of the 15th International Conference on Automated Deduction (CADE-98)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Lindau, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1421}, ISBN = {3-540-64675-2}, YEAR = {1998}, PAGES = {144--159}, ABSTRACT = {Variable overlaps are one of the main sources for the inefficiency of AC or ACU theorem proving calculi. In the presence of the axioms of abelian groups or at least cancellative abelian monoids, ordering restrictions allow us to avoid some of these overlaps, but inferences with unshielded variables remain necessary. In divisible torsion-free abelian groups, for instance the rational numbers, every clause can be transformed into an equivalent clause without unshielded variables. We show how such a variable elimination algorithm can be integrated into the cancellative superposition calculus. The resulting calculus is refutationally complete with respect to the axioms of divisible torsion-free abelian groups and allows us to dispense with variable overlaps altogether. If abstractions are performed eagerly, the calculus makes it furthermore possible to avoid the computation of AC unifiers and AC orderings.}, } @ARTICLE{Waldmann1998IPL, AUTHOR = {Waldmann, Uwe}, JOURNAL = {Information Processing Letters}, TITLE = {Extending reduction orderings to {ACU}-compatible reduction orderings}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {1}, PUBLISHER = {Elsevier}, MONTH = {July}, VOLUME = {67}, ISBN = {0020-0190}, YEAR = {1998}, PAGES = {43--49}, ABSTRACT = {We show that every reduction ordering over terms not containing $+$ that is total on ground terms and for which $0$ is minimal can be extended to an ordering that is ACU-compatible (or AC-compatible) and has the multiset property.To construct the extension ordering we use a variant of the self-labelling technique of Middeldorp, Ohsaki, and Zantema.}, } @INPROCEEDINGS{Waldmann1999LPAR, AUTHOR = {Waldmann, Uwe}, EDITOR = {Ganzinger, Harald and McAllester, David and Voronkov, Andrei}, TITLE = {Cancellative Superposition Decides the Theory of Divisible Torsion-Free Abelian Groups}, BOOKTITLE = {Proceedings of the 6th International Conference on Logic for Programming and Automated Reasoning (LPAR-99)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Tbilisi, Georgia}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1705}, ISBN = {3-540-66492-0}, YEAR = {1999}, PAGES = {131--147}, NOTE = {%Earlier version: Technical Report MPI-I-1999-2-003, Max-Planck-Institut f{\"u}r Informatik, Saarbr{\"u}cken}, ABSTRACT = {In divisible torsion-free abelian groups, the efficiency of the cancellative superposition calculus can be greatly increased by combining it with a variable elimination algorithm that transforms every clause into an equivalent clause without unshielded variables. We show that the resulting calculus is not only refutationally complete (even in the presence of arbitrary free function symbols), but that it is also a decision procedure for the theory of divisible torsion-free abelian groups.}, } @INPROCEEDINGS{Waldmann2001IJCAR, AUTHOR = {Waldmann, Uwe}, EDITOR = {Gor{\'e}, Rajeev and Leitsch, Alexander and Nipkow, Tobias}, TITLE = {Superposition and Chaining for Totally Ordered Divisible Abelian Groups ({Extended} Abstract)}, BOOKTITLE = {Automated reasoning : First International Joint Conference, IJCAR 2001}, PADDRESS = {Berlin, Germany}, ADDRESS = {Siena, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2083}, ISBN = {3-540-42254-4}, YEAR = {2001}, PAGES = {226--241}, ABSTRACT = {We present a calculus for first-order theorem proving in the presence of the axioms of totally ordered divisible abelian groups. The calculus extends previous superposition or chaining calculi for divisible torsion-free abelian groups and dense total orderings without endpoints. As its predecessors, it is refutationally complete and requires neither explicit inferences with the theory axioms nor variable overlaps. It offers thus an efficient way of treating equalities and inequalities between additive terms over, e.g., the rational numbers within a first-order theorem prover.}, } @ARTICLE{Waldmann2002aJSC, AUTHOR = {Waldmann, Uwe}, JOURNAL = {Journal of Symbolic Computation}, TITLE = {Cancellative Abelian Monoids and Related Structures in Refutational Theorem Proving ({Part I})}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {6}, PUBLISHER = {Elsevier}, MONTH = {June}, VOLUME = {33}, ISBN = {0747-7171}, YEAR = {2002}, PAGES = {777--829}, ABSTRACT = {We present superposition calculi in which the axioms of cancellative abelian monoids and, optionally, the torsion-freeness axiom are integrated. Cancellative abelian monoids comprise abelian groups, but also such ubiquitous structures as the natural numbers or multisets. Our calculi require neither extended clauses nor explicit inferences with the theory axioms. Compared with AC-superposition calculi, the number of variable overlaps is significantly reduced by strong ordering restrictions. }, } @ARTICLE{Waldmann2002bJSC, AUTHOR = {Waldmann, Uwe}, JOURNAL = {Journal of Symbolic Computation}, TITLE = {Cancellative Abelian Monoids and Related Structures in Refutational Theorem Proving ({Part II})}, ADDRESS = {Amsterdam, the Netherlands}, NUMBER = {6}, PUBLISHER = {Elsevier}, MONTH = {June}, VOLUME = {33}, ISBN = {0747-7171}, YEAR = {2002}, PAGES = {831--861}, ABSTRACT = {Cancellative superposition is a refutationally complete calculus for first-order equational theorem proving in the presence of the axioms of cancellative abelian monoids, and, optionally, the torsion-freeness axioms. Thanks to strengthened ordering restrictions, cancellative superposition avoids some of the inefficiencies of classical AC-superposition calculi. We show how the efficiency of cancellative superposition can be further improved by using variable elimination techniques, leading to a significant reduction of the number of variable overlaps. In particular, we demonstrate that in divisible torsion-free abelian groups, variable overlaps, AC-unification and AC-orderings can be avoided completely.}, } @INPROCEEDINGS{Waldmann2002IUC, AUTHOR = {Waldmann, Uwe}, TITLE = {A New Input Technique for Accented Letters in Alphabetical Scripts}, BOOKTITLE = {Proceedings of the 20th International Unicode Conference}, PADDRESS = {Mountain View, CA, USA}, ADDRESS = {Washington, DC, USA}, PUBLISHER = {The Unicode Consortium}, MONTH = {January}, YEAR = {2002}, PAGES = {C12}, ABSTRACT = {SITMO is a new input technique for accented and special letters of the Latin alphabet (or other alphabets of comparable size), which combines in a uniform way short key sequences for frequently used characters with an easily memorizable scheme to enter rarely used characters. Compared with traditional modifier techniques, SITMO requires less additional keys and allows to access more characters, while for most European languages, the average number of keystrokes per derived letter is similar (that is, close to 2).}, } @ARTICLE{Waldmann92a, AUTHOR = {Waldmann, Uwe}, JOURNAL = {Theoretical Computer Science}, TITLE = {Semantics of Order-Sorted Specifications}, NUMBER = {1}, PUBLISHER = {North-Holland Publishing Co.}, VOLUME = {94}, ISBN = {0304-3975}, YEAR = {1992}, PAGES = {1--35}, ABSTRACT = {Order-sorted specifications (i.e., many-sorted specifications with subsort relations) have been proved to be a useful tool for the description of partially defined functions and error handling in abstract data types. \par Several definitions for order-sorted algebras have been proposed. In some papers an operator symbol, which may be multiply declared, is interpreted by a family of functions (``overloaded'' algebras), in other papers it is always interpreted by a single function (``non-overloaded'' algebras). On the one hand, we try to demonstrate the differences between these two approaches with respect to equality, rewriting, and completion; on the other hand, we prove that in fact both theories can be studied parallelly, provided that certain notions are suitably defined. \par The overloaded approach differs from the many-sorted and the non-overloaded case, in that the overloaded term algebra is not necessarily initial. We give a decidable sufficient criterion for the initiality of the term algebra, which is less restrictive than GJM-regularity as proposed by Goguen, Jouannaud, and Meseguer. \par Sort decreasingness is an important property of rewrite system, since it ensures that confluence and Church-Rosser property are equivalent, that the overloaded and non-overloaded rewrite relations agree, and that variable overlaps do not yield critical pairs. We prove that it is decidable whether or not a rewrite rule is sort decreasing, even if the signature is not regular. \par Finally we demonstrate that every overloaded completion procedure may also be used in the non-overloaded world, but not conversely, and that specifications exist that can only be completed using the non-overloaded semantics.}, } @INPROCEEDINGS{Wang97, AUTHOR = {Wang, Yongge}, EDITOR = {Rolim, Jos{\'e}}, TITLE = {Randomization and Approximation Techniques in Computer Science}, BOOKTITLE = {Proceedings of the International Workshop on Randomization and Approximation Techniques in Computer Science (RANDOM-97)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Bologna, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture notes in computer science}, VOLUME = {1269}, ISBN = {3-540-63248-4}, YEAR = {1997}, PAGES = {209--225}, } @ARTICLE{WangIPL96a, AUTHOR = {Wang, Yongge}, JOURNAL = {Information Processing Letters}, TITLE = {NP-hard sets are superterse unless NP is small}, NUMBER = {1}, PUBLISHER = {Elsevier}, VOLUME = {61}, YEAR = {1997}, PAGES = {1--6}, } @ARTICLE{WangTCS96, AUTHOR = {Wang, Yongge}, JOURNAL = {Theory of Computing Systems}, TITLE = {Randomness, Stochasticity, and Approximation}, ADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, VOLUME = {32}, YEAR = {1999}, PAGES = {517--529}, } @INPROCEEDINGS{WBH+02-CADE18, AUTHOR = {Weidenbach, Christoph and Brahm, Uwe and Hillenbrand, Thomas and Keen, Enno and Theobalt, Christian and Topi{\'c}, Dalibor}, EDITOR = {Voronkov, Andrei}, TITLE = {{SPASS} Version 2.0}, BOOKTITLE = {Automated deduction, CADE-18 : 18th International Conference on Automated Deduction}, PADDRESS = {Heidelberg, Germany}, ADDRESS = {Kopenhagen, Denmark}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2392}, ISBN = {3-540-43931-5}, YEAR = {2002}, PAGES = {275--279}, ABSTRACT = {SPASS is an automated theorem prover for full first-order logic with equality. This system description provides an overview of recent developments in SPASS 2.0, including among others an implementation of contextual rewriting, refinements of the clause normal form transformation, and enhancements of the inference engine.}, } @ARTICLE{Weidenbach1999jar, AUTHOR = {Weidenbach, Christoph}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {{SPASS V0.95TPTP}}, NUMBER = {1}, PUBLISHER = {Kluwer}, VOLUME = {23}, ISBN = {0168-7433}, YEAR = {1999}, PAGES = {21--21}, } @PHDTHESIS{Weidenbach2000habil, AUTHOR = {Weidenbach, Christoph}, TITLE = {{Entscheidbarkeitsprobleme f{\"u}r monadische (Horn)Klauselklassen}}, SCHOOL = {Universit{\"a}t des Saarlandes, Naturwissenschaftlich-Technische Fakult{\"a}t}, TYPE = {Habilitation thesis}, MONTH = {June}, YEAR = {2000}, ABSTRACT = {Abstract der Antrittsvorlesung: Heute lassen sich mit modernen Beweissystemen fuer die klassische Praedikatenlogik eine Reihe von aktuellen Problemen wie die Analyse von Programmen oder (Sicherheits)Protokollen vollautomatisch loesen. Dies ist das Resultat einer Reihe von neuen Techniken/Ergebnissen, die in Form von Kalkuelen, Redundanzkriterien, Algorithmen und Implementierungsdesigns Einzug in aktuelle Systeme gehalten haben. In der Vorlesung werde ich, ausgehend von der Eingabe des Beweissystems, einer Formel, bis hin zu seinem Resultat bei Terminierung, dem Beweis oder der saturierten und damit erfuellbaren Klauselmenge, die in dem SPASS-Beweissystem realisierten Techniken vorstellen und sie aus theoretischer, pragmatischer und Implementierungssicht diskutieren und demonstrieren.}, } @INCOLLECTION{Weidenbach2001handbook, AUTHOR = {Weidenbach, Christoph}, EDITOR = {Robinson, Alan and Voronkov, Andrei}, TITLE = {Combining Superposition, Sorts and Splitting}, BOOKTITLE = {Handbook of Automated Reasoning}, CHAPTER = {27}, ADDRESS = {Amsterdam, the Netherlands}, PUBLISHER = {Elsevier}, MONTH = {January}, VOLUME = {1}, YEAR = {2001}, PAGES = {1965--2013}, } @INPROCEEDINGS{Weidenbach92a, AUTHOR = {Weidenbach, Christoph}, EDITOR = {Ohlbach, Hans J{\"u}rgen}, TITLE = {A New Sorted Logic}, BOOKTITLE = {GWAI-92: Advances in Artificial Inteligence, Proceedings 16th German Workshop on Artificial Intelligence}, PADDRESS = {Berlin, Germany}, ADDRESS = {Bonn}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {671}, YEAR = {1993}, PAGES = {43--54}, ABSTRACT = {We present a sound and complete calculus for an expressive sorted first-order logic. Sorts are extended to the semantic and pragmatic use of unary predicates. A sort may denote an empty set and the sort structure can be created by making use of the full first-order language. Technically spoken, we allow sort declarations to be used in the same way than ordinary atoms. Therefore we can compile every first-order logic formula into our logic.\\ The extended expressivity implies an extended sorted inference machine. We present a new unification algorithm and show that the declarations the unification algorithm is built on have to be changed dynamically during the deduction process. Deductions in the resulting resolution calculus are very efficient compared to deductions in the unsorted resolution calculus. The approach is a conservative extension of the known sorted approaches, as it simplifies to the known sorted calculi if we apply the calculus to the much more restricted input formulas of these calculi.}, } @INPROCEEDINGS{Weidenbach93a, AUTHOR = {Weidenbach, Christoph}, EDITOR = {Bajcsy, R.}, TITLE = {Extending the Resolution Method with Sorts}, BOOKTITLE = {Proceedings of the 13th International Joint Conference on Artificial Intelligence (IJCAI '93)}, PADDRESS = {San Mateo, CA}, ADDRESS = {Chambery, France}, PUBLISHER = {Morgan Kaufmann}, VOLUME = {1}, YEAR = {1993}, PAGES = {60--65}, ABSTRACT = {In this paper I extend the standard first-order resolution method with special reasoning mechanisms for sorts. Sorts are one place predicates. Literals built from one place predicates are called sort literals. Negative sort literals can be compiled into restrictions of the relevant variables to sorts or can be deleted if they fulfill special conditions. Positive sort literals define the sort structure for sorted unification. Sorted unification exploits the sort restrictions of variables. As the occurrence of sort literals is not restricted, it might be necessary to add additional literals to resolvents and factors and to dynamically change the set of positive sort literals used by sorted unification during the deduction process. The calculus I propose thus extends the standard resolution method by sorted unification, residue literals and a dynamic processing of the sort information. I show that this calculus generalizes and improves existing approaches to sorted reasoning. Finally I give some applications to automated theorem proving and abduction.}, } @INPROCEEDINGS{Weidenbach94a, AUTHOR = {Weidenbach, Christoph}, EDITOR = {Broda, Krysia and D'Agostino, Marcello and et. al.}, TITLE = {First-Order Tableaux with Sorts}, BOOKTITLE = {TABLEAUX-'94, 3rd Workshop on Theorem Proving with Analytic Tableaux and Related Methods}, ADDRESS = {Marseille, France}, PUBLISHER = {Imperial College of Science Technology and Medicine, TR-94/5}, MONTH = {April}, YEAR = {1994}, PAGES = {247--261}, NOTE = {To appear in the Bulletin of IGPL}, ABSTRACT = {Tableau and the free variable tableau are extended with sorts. Sorts are sets of unary predicates. They can be attached to variables. Semantically, the domain of a variable is restricted to the intersection of the denotations of the attached predicates. Syntactically, the sort information is exploited by modified $\gamma$ and $\delta$ rules. The standard unification algorithm of free variable tableau is replaced by a sorted unification algorithm. The resulting calculi, tableau with sorts and free variable tableau with sorts are proved sound, complete and more suitable for mechanization than their counterparts without sorts.}, } @INPROCEEDINGS{Weidenbach94c, AUTHOR = {Weidenbach, Christoph}, EDITOR = {Kunze, J{\"u}rgen and Stoyan, Herbert}, TITLE = {Sorts, Resolution, Tableaux and Propositional Logic}, BOOKTITLE = {KI-94 Workshops: Extended Abstracts}, PADDRESS = {Bonn, Germany}, ADDRESS = {Saarbr{\"u}cken, Germany}, PUBLISHER = {Gesellschaft f{\"u}r Informatik}, YEAR = {1994}, PAGES = {315--316}, } @ARTICLE{Weidenbach95d, AUTHOR = {Weidenbach, Christoph}, JOURNAL = {Journal of the Interest Group in Pure and Applied Logics}, TITLE = {First-Order Tableaux with Sorts}, NUMBER = {6}, VOLUME = {3}, YEAR = {1995}, PAGES = {887--906}, } @INPROCEEDINGS{Weidenbach95e, AUTHOR = {Barth, Peter and Kleine B{\"u}ning, Hans and Weidenbach, Christoph}, EDITOR = {Dreschler-Fischer, Leonie and Pribbenow, Simone}, TITLE = {Workshop CPL Computational Propositional Logic}, BOOKTITLE = {KI-95 Activities: Workshops, Posters, Demos}, ORGANIZATION = {Gesellschaft f{\"u}r Informatik e.V.}, PADDRESS = {Bonn, Germany}, ADDRESS = {Bielefeld, Germany}, PUBLISHER = {Gesellschaft f{\"u}r Informatik}, YEAR = {1995}, PAGES = {71--72}, } @INPROCEEDINGS{Weidenbach96a, AUTHOR = {Weidenbach, Christoph}, EDITOR = {McRobbie, M. A. and Slaney, J. K.}, TITLE = {Unification in Pseudo-Linear Sort Theories is Decidable}, BOOKTITLE = {Proceedings of the 13th International Conference on Automated Deduction (CADE-13)}, PADDRESS = {Berlin, Germany}, ADDRESS = {New Brunswick, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1104}, ISBN = {3-540-61511-3}, YEAR = {1996}, PAGES = {343--357}, } @INPROCEEDINGS{Weidenbach96b, AUTHOR = {Weidenbach, Christoph and Gaede, Bernd and Rock, Georg}, EDITOR = {McRobbie, M. A. and Slaney, J. K.}, TITLE = {{SPASS} \& {FLOTTER}, Version 0.42}, BOOKTITLE = {Proceedings of the 13th International Conference on Automated Deduction (CADE-13)}, PADDRESS = {Berlin, Germany}, ADDRESS = {New Brunswick, USA}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1104}, ISBN = {3-540-61511-3}, YEAR = {1996}, PAGES = {141--145}, } @INPROCEEDINGS{Weidenbach96c, AUTHOR = {Weidenbach, Christoph}, EDITOR = {Schulz, Klaus U. and Kepser, Stephan}, TITLE = {Unification in Sort Theories}, BOOKTITLE = {Proceedings of the 10th International Workshop on Unification, UNIF'96}, PADDRESS = {M{\"u}nchen, Germany}, ADDRESS = {Harsching, Germany}, NUMBER = {91}, PUBLISHER = {Universit{\"a}t M{\"u}nchen}, SERIES = {CIS-Bericht}, VOLUME = {96}, YEAR = {1996}, PAGES = {16--25}, } @INPROCEEDINGS{Weidenbach96d, AUTHOR = {Weidenbach, Christoph}, EDITOR = {Hermann, Miki and Salzer, Gernot}, TITLE = {Sorted Unification and Its Application to Automated Theorem Proving}, BOOKTITLE = {Proceedings of the CADE-13 Workshop: Term Schematizations and Their Applications}, ADDRESS = {New Brunswick, USA}, PUBLISHER = {Self}, YEAR = {1996}, PAGES = {67--76}, NOTE = {To appear in form of a technical report at the University of Wien, Austria}, } @PHDTHESIS{Weidenbach96e, AUTHOR = {Weidenbach, Christoph}, TITLE = {Computational Aspects of a First-Order Logic with Sorts}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, YEAR = {1996}, } @ARTICLE{Weidenbach96f, AUTHOR = {Weidenbach, Christoph}, JOURNAL = {Annals of Mathematics and Artificial Intelligence}, TITLE = {Unification in Sort Theories and its Applications}, NUMBER = {2/4}, PUBLISHER = {Baltzer}, VOLUME = {18}, ISBN = {1012-2443}, YEAR = {1996}, PAGES = {261--293}, } @ARTICLE{Weidenbach97jar, AUTHOR = {Weidenbach, Christoph}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {{SPASS} Version 0.49}, NUMBER = {2}, PUBLISHER = {Kluwer}, MONTH = {April}, VOLUME = {18}, ISBN = {0168-7433}, YEAR = {1997}, PAGES = {247--252}, } @INCOLLECTION{Weidenbach98kluwer, AUTHOR = {Weidenbach, Christoph}, EDITOR = {Bibel, Wolfgang and Schmitt, Peter H.}, TITLE = {Sorted Unification and Tree Automata}, BOOKTITLE = {Automated Deduction - A Basis for Applications}, CHAPTER = {9}, ADDRESS = {Dordrecht, The Netherlands}, PUBLISHER = {Kluwer}, MONTH = {January}, SERIES = {Applied Logic}, YEAR = {1998}, PAGES = {291--320}, } @INCOLLECTION{Weidenbach98teubner, AUTHOR = {Weidenbach, Christoph}, EDITOR = {Fiedler, Herbert and Gorny, Peter and Grass, Werner and H{\"o}lldobler, Steffen and Hotz, G{\"u}nter and Kerner, I. O. and Reischuk, R{\"u}diger}, TITLE = {{Rechnen in sortierter Pr{\"a}dikatenlogik}}, BOOKTITLE = {Ausgezeichnete Informatikdissertationen 1997}, ADDRESS = {Stuttgart, Germany}, PUBLISHER = {Teubner}, MONTH = {January}, YEAR = {1998}, PAGES = {183--197}, } @INPROCEEDINGS{Weidenbach99cade, AUTHOR = {Weidenbach, Christoph}, EDITOR = {Ganzinger, Harald}, TITLE = {Towards an Automatic Analysis of Security Protocols in First-Order Logic}, BOOKTITLE = {Proceedings of the 16th International Conference on Automated Deduction (CADE-16)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Trento, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1632}, YEAR = {1999}, PAGES = {378--382}, } @INPROCEEDINGS{Weidenbach99cadespass, AUTHOR = {Weidenbach, Christoph and Afshordel, Bijan and Brahm, Uwe and Cohrs, Christian and Engel, Thorsten and Keen, Enno and Theobalt, Christian and Topi{\'c}, Dalibor}, EDITOR = {Ganzinger, Harald}, TITLE = {System Description: {SPASS} Version 1.0.0}, BOOKTITLE = {Proceedings of the 16th International Conference on Automated Deduction (CADE-16)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Trento, Italy}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1632}, ISBN = {3-540-66222-7}, YEAR = {1999}, PAGES = {314--318}, } @ARTICLE{WeidenbachMeyerEtAl98jar, AUTHOR = {Weidenbach, Christoph and Meyer, Christoph and Cohrs, Christian and Engel, Thorsten and Keen, Enno}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {{SPASS V0.77}}, NUMBER = {1}, PUBLISHER = {Kluwer}, VOLUME = {21}, ISBN = {0168-7433}, YEAR = {1998}, PAGES = {113--113}, } @INPROCEEDINGS{WernerBockmayrKrischer93f, AUTHOR = {Werner, Andreas and Bockmayr, Alexander and Krischer, Stefan}, EDITOR = {M{\"u}ck, A.}, TITLE = {How to Realize {LSE} Narrowing}, BOOKTITLE = {Proceedings of the 2nd International Workshop on Functional/Logic Programming}, PADDRESS = {M{\"u}nchen, Germany}, ADDRESS = {Rattenberg}, PUBLISHER = {LMU M{\"u}nchen, Technical Report 9311}, MONTH = {October}, YEAR = {1993}, } @INPROCEEDINGS{WernerBockmayrKrischer93g, AUTHOR = {Werner, Andreas and Bockmayr, Alexander and Krischer, Stefan}, EDITOR = {Beierle, C.}, TITLE = {A Concept for the Implementation of {LSE} Narrowing}, BOOKTITLE = {9.~Workshop Logische Programmierung}, PADDRESS = {Hagen}, ADDRESS = {Hagen}, PUBLISHER = {{FU Hagen, Informatik Bericht 146} -- 10/1993}, YEAR = {1993}, } @TECHREPORT{WernerBockmayrKrischer93i, AUTHOR = {Werner, Andreas and Bockmayr, Alexander and Krischer, Stefan}, TITLE = {How to Realize {LSE} Narrowing}, INSTITUTION = {Fakult{\"a}t f{\"u}r Informatik, Universit{\"a}t Karlsruhe}, ADDRESS = {Karlsruhe}, NUMBER = {6/93}, YEAR = {1993}, } @INPROCEEDINGS{WernerBockmayrKrischer94, AUTHOR = {Werner, Andreas and Bockmayr, Alexander and Krischer, Stefan}, EDITOR = {Levi, Giorgio and Rodr{\'i}guez-Artalejo, Mario}, TITLE = {How to realize {LSE} narrowing}, BOOKTITLE = {Proceedings of the 4th International Conference on Algebraic and Logic Programming (ALP'94)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Madrid, Spain}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {850}, YEAR = {1994}, PAGES = {59--76}, ABSTRACT = {Narrowing is a complete unification procedure for equational theories defined by canonical term rewriting systems. It is also the operational semantics of various logic and functional programming languages. In an earlier paper, we introduced the LSE narrowing strategy which is complete for arbitrary canonical rewriting systems and optimal in the sense that two different LSE narrowing derivations cannot generate the same narrowing substitution. LSE narrowing improves all previously known strategies for arbitrary systems. According to their definition, LSE narrowing steps seem to be very expensive, because a large number of subterms has to be checked for reducibility. In this paper, we first show that many of these subterms are identical. Then we describe how using left-to-right basic occurrences the number of subterms that have to be tested can be reduced drastically. Finally, based on these theoretical results, we develop an efficient implementation of LSE narrowing.}, } @ARTICLE{WernerBockmayrKrischer98, AUTHOR = {Werner, Andreas and Bockmayr, Alexander and Krischer, Stefan}, JOURNAL = {New Generation Computing}, TITLE = {How to realize {LSE} narrowing}, NUMBER = {4}, VOLUME = {16}, ISBN = {0288-3635}, YEAR = {1998}, PAGES = {397--434}, ABSTRACT = {Narrowing is a complete unification procedure for equational theories defined by canonical term rewriting systems. It is also the operational semantics of various logic and functional programming languages. In an earlier paper, we introduced the LSE narrowing strategy which is complete for arbitrary canonical rewriting systems and optimal in the sense that two different LSE narrowing derivations cannot generate the same narrowing substitution. LSE narrowing improves all previously known strategies for the class of arbitrary canonical systems. LSE narrowing detects redundant derivations by reducibility tests. According to their definition, LSE narrowing steps seem to be very expensive, because a large number of subterms has to be tested. In this paper, we show that many of these subterms are identical. We describe how left-to-right basic occurrences can be used to identify and exclude these identical subterms. This way, we can drastically reduce the number of subterms that have to be tested. Based on these theoretical results, we develop an efficient implementation of LSE narrowing.}, } @INPROCEEDINGS{Weydert1998a, AUTHOR = {Weydert, Emil}, EDITOR = {Cohn, Anthony G. and Schubert, Lenhart and Shapiro, Stuart C.}, TITLE = {System JZ : How to build a canonical ranking model of a default knowledge base}, BOOKTITLE = {Proceedings of the 6th International Conference on Principles of Knowledge Representation and Reasoning (KR-98)}, PADDRESS = {San Francisco, USA}, ADDRESS = {Trento, Italy}, PUBLISHER = {Morgan Kaufmann}, YEAR = {1998}, PAGES = {190--201}, } @INPROCEEDINGS{Weydert1998b, AUTHOR = {Weydert, Emil}, EDITOR = {Delgrande, Jim and Truszczynski, Mirek}, TITLE = {Minimal information entailment : A preliminary account}, BOOKTITLE = {Proceedings of the 7th International Workshop on Nonmonotonic Reasoning (Workshop on Formal Aspects and Applications of Nonmonotonic Reasoning)}, PADDRESS = {-}, ADDRESS = {Trento, Italy}, PUBLISHER = {-}, MONTH = {July}, YEAR = {1998}, PAGES = {64--72}, } @INPROCEEDINGS{Weydert1998c, AUTHOR = {Weydert, Emil and van der Torre, Leendert W. N.}, EDITOR = {Lang, Jerome}, TITLE = {Goals, desires, utilities and preferences}, BOOKTITLE = {Proceedings of the ECAI-98 Workshop : Decision theory meets artificial intelligence - qualitative and quantitative approaches}, PADDRESS = {Brighton, UK}, ADDRESS = {Brighton, United Kingdom}, PUBLISHER = {ECAI}, YEAR = {1998}, PAGES = {57--64}, } @MISC{Weydert1998d, AUTHOR = {Weydert, Emil}, TITLE = {Some Notes on Nonmonotonic Probabilistic Inference}, HOWPUBLISHED = {Working notes of a tutorial at the 10th European Summer School in Logic, Language and Information}, MONTH = {August}, YEAR = {1998}, } @INCOLLECTION{Weydert1999, AUTHOR = {Weydert, Emil}, EDITOR = {de Leon, David and Wallin, Annika and Hulth, Nils}, TITLE = {{JZBR} - Iterated Belief Change for Conditional Ranking Constraints}, BOOKTITLE = {Spinning Ideas - Electronic Essays Dedicated to Peter Gaerdenfors on His Fiftieth Birthday}, TYPE = {Electronic publication}, ADDRESS = {Lund, Sweden}, PUBLISHER = {Lund University Cognitive Science}, MONTH = {January}, YEAR = {1999}, PAGES = {1--11}, } @INPROCEEDINGS{Weydert1999a, AUTHOR = {Weydert, Emil}, EDITOR = {Rott, Hans and Albert, Chris and Brewka, Gerd and Witteveen, Cees}, TITLE = {{JZBR} - Iterated Belief Change for Conditional Ranking Constraints}, BOOKTITLE = {Proceedings of the 4th Dutch-German Workshop on Nonmonotonic Reasoning Techniques and their Applications (DGNMR-99)}, PADDRESS = {Amsterdam, The Netherlands}, ADDRESS = {Amsterdam, The Netherlands}, PUBLISHER = {ILLC Scientific Publications}, ISBN = {1389-3033}, YEAR = {1999}, PAGES = {57--66}, } @INPROCEEDINGS{Weydert1999b, AUTHOR = {Weydert, Emil and van der Torre, Leendert W. N.}, EDITOR = {John Bell}, TITLE = {Risk parameters for utilitarian desires}, BOOKTITLE = {Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI-99), Workshop on Practial Reasoning and Rationality}, PADDRESS = {Stockholm, Sweden}, ADDRESS = {Stockholm, Sweden}, PUBLISHER = {IJCAI}, YEAR = {1999}, PAGES = {48--54}, } @INPROCEEDINGS{Weydert2000a, AUTHOR = {Weydert, Emil}, EDITOR = {Horn, Werner}, TITLE = {How to revise ranked probabilities}, BOOKTITLE = {Proceedings of the 14th European Conference on Artificial Intelligence (ECAI-00)}, PADDRESS = {Amsterdam, the Netherlands}, ADDRESS = {Berlin, Germany}, PUBLISHER = {IOS Press}, MONTH = {August}, SERIES = {Frontiers in Artificial Intelligence and Applications}, VOLUME = {54}, ISBN = {1-58603-013-2}, YEAR = {2000}, PAGES = {38--42}, } @INPROCEEDINGS{Weydert2000b, AUTHOR = {Weydert, Emil}, TITLE = {Thoughts on Evolving Science and Belief}, BOOKTITLE = {Proceedings of the Workshop "Scientific Reasoning in AI and Philosophy of Science" at the 14th European Conference on Artificial Intelligence (ECAI-00)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Berlin, Germany}, PUBLISHER = {ECAI}, YEAR = {2000}, PAGES = {62--69}, } @INPROCEEDINGS{Weydert2000c, AUTHOR = {Weydert, Emil}, EDITOR = {Cunningham, Jim and Gabbay, Dov}, TITLE = {Rankings in flux}, BOOKTITLE = {Proceedings of the 3rd International Conference on Formal and Applied Practical Reasoning (FAPR-00)}, PADDRESS = {London, UK}, ADDRESS = {London, United Kingdom}, PUBLISHER = {Imperial College Department of Computing}, MONTH = {September}, ISBN = {ISSN 1469-4166}, YEAR = {2000}, PAGES = {37--48}, } @INPROCEEDINGS{Weydert2001a, AUTHOR = {Lang, J{\'e}r{\^{o}}me and van der Torre, Leendert W. N. and Weydert, Emil}, EDITOR = {Parsons, Simon and Gmytrasiewicz, Piotr}, TITLE = {Two Kinds of Conflicts between Desires (and how to resolve them)}, BOOKTITLE = {Proceedings of the AAAI Symposium on Game and Decision Theoretic Agents}, PADDRESS = {Menlo Park, USA}, ADDRESS = {Stanford, USA}, PUBLISHER = {AAAI}, MONTH = {March}, SERIES = {AAAI Spring Symposium Series}, VOLUME = {SS-00-03}, ISBN = {1-57735-131-2}, YEAR = {2001}, PAGES = {54--59}, } @INPROCEEDINGS{Weydert2001b, AUTHOR = {Weydert, Emil}, EDITOR = {Brewka, Gerhard and Witteveen, Cees and Schaub, Torsten}, TITLE = {Rankings we prefer: a rational minimal construction semantics for default reasoning}, BOOKTITLE = {Proceedings of the 5th Dutch-German Workshop on Nonmonotonic Reasoning Techniques and their Applications (DGNMR-01)}, PADDRESS = {Potsdam, Germany}, ADDRESS = {Potsdam, Germany}, PUBLISHER = {Institut f{\"u}r Informatik, Universit{\"a}t Potsdam}, MONTH = {April}, YEAR = {2001}, PAGES = {1--12}, } @ARTICLE{Weydert2001c, AUTHOR = {van der Torre, Leendert W. N. and Weydert, Emil}, JOURNAL = {Applied Artificial Intelligence}, TITLE = {Parameters for Utilitarian Desires in a Qualitative Decision Theory}, PUBLISHER = {Taylor \& Francis}, MONTH = {January}, VOLUME = {14}, ISBN = {0883-9514}, YEAR = {2001}, PAGES = {285--301}, } @ARTICLE{Weydert2001d, AUTHOR = {Weydert, Emil}, JOURNAL = {KI - K{\"u}nstliche Intelligenz}, TITLE = {Defaults, Logic and Probability - A theoretical perspective}, PUBLISHER = {arendtap Desktop Publishing Agentur, Verlags- und Vertriebs GmbH}, VOLUME = {4/01}, ISBN = {0933-1875}, YEAR = {2001}, PAGES = {44--49}, ABSTRACT = {The complexity of the real world and the restricted availability of knowledge call for powerful logical frameworks to deal with uncertainty, reaching from qualitative default formalisms to quantitative probability logics. In particular, reasoning under uncertainty requires defeasible inference notions. We take a general look at these issues, with a special emphasis on quasi-probabilistic approaches to default reasoning.}, } @INPROCEEDINGS{Weydert2001e, AUTHOR = {Weydert, Emil}, EDITOR = {Benferhat, Salem and Besnard, Philippe}, TITLE = {Rankings we prefer: a minimal construction semantics for default reasoning}, BOOKTITLE = {Proceedings of the 6th European Conference on Symbolic and Quantitative Approaches to Reasoning with Uncertainty (ECSQARU-01)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Toulouse, France}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {2143}, YEAR = {2001}, PAGES = {616--627}, } @ARTICLE{Weydert2001f, AUTHOR = {Lang, J{\'e}r{\^{o}}me and van der Torre, Leendert W. N. and Weydert, Emil}, JOURNAL = {Autonomous Agents and Multi-Agent Systems}, TITLE = {Utilitarian Desires}, ADDRESS = {Dordrecht, the Netherlands}, NUMBER = {3}, PUBLISHER = {Kluwer}, VOLUME = {5}, ISBN = {1387-2532}, YEAR = {2002}, PAGES = {329--363}, } @INPROCEEDINGS{Weydert93a, AUTHOR = {Weydert, Emil}, EDITOR = {Clarke, M. and Kruse, R. and Moral, S.}, TITLE = {Plausible Inference for Default Conditionals}, BOOKTITLE = {Symbolic and Quantitative Approaches to Reasoning and Uncertainty: Proceedings of the European Conference ECSQARU '93}, PADDRESS = {Berlin, Germany}, ADDRESS = {Granada, Spain}, PUBLISHER = {Springer}, MONTH = {December}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {747}, YEAR = {1993}, PAGES = {356--363}, NOTE = {Also in Proc.~IJCAI-Workshop: Conditionals in Knowledge Representation, 1993}, ABSTRACT = {This paper presents a monotonic core logic for default conditionals and investigates possible nonmonotonic extensions. First, we introduce a possible worlds semantics characterizing HRC0, a strong logic for non-nested normal implication. Next, we formulate several basic regularity postulates for defeasible entailment relations extending our monotonic inference relation and claiming to provide an appropriate interpretation of our default conditional. We then construct a preferential semantic framework describing a class of consequence relations verifying our standard requirements. In particular, we define and analyze elementary hyperentailment, a new semantic-based plausible inference relation for boolean combinations of facts and defaults.}, } @INPROCEEDINGS{Weydert93b, AUTHOR = {Weydert, Emil}, EDITOR = {Nejdl, W.}, TITLE = {Default Quantifiers: {A}bout Plausible Reasoning in First-Order Contexts}, BOOKTITLE = {Working Notes of the Dutch/German Workshop on Nonmonotonic Reasoning Techniques and their Applications}, PADDRESS = {Aachen, Germany}, ADDRESS = {Aachen, Germany}, PUBLISHER = {Rheinisch-Westf{\"a}lische Technische Hochschule Aachen}, YEAR = {1993}, ABSTRACT = {In this paper, we extend first-order logic by a generalized, dyadic default quantifier, which is shown to be required for accurately representing more complex forms of default knowledge. We propose a general qualitative measure semantics and provide a sound and complete proof theory for the resulting monotonic entailment relation. We then present a suitable semantic-based nonmonotonic extension, normality maximization entailment, appropriate for first-order contexts, satisfying a defeasible deduction principle and verifying inference patterns like defeasible modus ponens and defeasible chaining. We discuss some representative examples and compare our proposal to other conditional frameworks.}, } @INPROCEEDINGS{Weydert94a, AUTHOR = {Weydert, Emil}, TITLE = {General Belief Measures}, BOOKTITLE = {Proceedings of the 10th Conference on Uncertainty in Artificial Intelligence}, PADDRESS = {San Mateo, CA}, ADDRESS = {University of Washington, Seattle, WA}, PUBLISHER = {Morgan Kaufmann}, YEAR = {1994}, PAGES = {575--582}, ABSTRACT = {We introduce a minimal quasi-probabilistic valuation concept and investigate two particularly interesting subclasses of generalized measures : 1. Ranking measures, which subsume Spohn-type and possibility valuations, 2. Cumulative measures, which combine the probabilistic and the ranking philosophy, paving the way to a fine-grained, dynamic account of plain belief in first-order contexts.}, } @INPROCEEDINGS{Weydert94b, AUTHOR = {Weydert, Emil}, EDITOR = {Lakemeyer, Gerhard and Nebel, Bernhard}, TITLE = {Hyperrational Conditionals}, BOOKTITLE = {Foundations of Knowledge Representation and Reasoning}, PADDRESS = {Berlin, Germany}, PUBLISHER = {Springer}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {810}, YEAR = {1994}, PAGES = {310--332}, } @INPROCEEDINGS{Weydert95, AUTHOR = {Weydert, Emil}, EDITOR = {Froideveaux, Christine and Kohlas, J{\"u}rg}, TITLE = {Numeric Defaults. About an expressive first-order framework for reasoning with infinitesimal probabilities}, BOOKTITLE = {Symbolic and Quantitative Approaches to Reasoning and Uncertainty (ECSQARU 95)}, PADDRESS = {Berlin, Germany}, ADDRESS = {Fribourg, Switzerland}, PUBLISHER = {Springer}, MONTH = {July}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {946}, ISBN = {3-540-60112-0}, YEAR = {1995}, PAGES = {420--427}, } @INPROCEEDINGS{Weydert95b, AUTHOR = {Weydert, Emil}, EDITOR = {Wachsmuth, Ipke and Rollinger, Claus-Rainer and Brauer, Wilfried}, TITLE = {Default Entailment. A preferential construction semantics for defeasible inference}, BOOKTITLE = {Advances in Artificial Intelligence: Proceedings of the 19th German Annual Conference on Artificial Intelligence}, PADDRESS = {Berlin, Germany}, ADDRESS = {Bielefeld, Germany}, PUBLISHER = {Springer}, MONTH = {September}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {981}, ISBN = {3-540-60343-3}, YEAR = {1995}, PAGES = {173--184}, } @INPROCEEDINGS{Weydert95c, AUTHOR = {Weydert, Emil}, EDITOR = {Besnard, Philippe and Hanks, Steve}, TITLE = {Defaults and Infinitesimals. Defeasible inference by nonarchimedean entropy maximization}, BOOKTITLE = {Proceedings of the 11th Conference on Uncertainty in Artificial Intelligence (UAI 95)}, PADDRESS = {San Francisco, USA}, ADDRESS = {Montr{\'e}al, Canada}, PUBLISHER = {Morgan Kaufmann}, MONTH = {August}, ISBN = {1-55860-385-9}, YEAR = {1995}, PAGES = {540--547}, } @INPROCEEDINGS{Weydert96a, AUTHOR = {Weydert, Emil}, EDITOR = {Gabbay, Dov and Ohlbach, Hans J{\"u}rgen}, TITLE = {System J - Revision Entailment: Default Reasoning through Ranking Measure Updates}, BOOKTITLE = {Practical Reasoning - International Conference on Formal and Applied Practical Reasoning, FAPR'96}, PADDRESS = {Berlin, Germany}, ADDRESS = {Bonn, Germany}, PUBLISHER = {Springer}, MONTH = {June}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {1085}, ISBN = {3-540-61313-7}, YEAR = {1996}, PAGES = {637--649}, } @INPROCEEDINGS{Weydert96b, AUTHOR = {Weydert, Emil}, EDITOR = {Niemel{\"a}, Ilkka}, TITLE = {Default Quantifier Logic}, BOOKTITLE = {Proceedings of the ECAI'96 Workshop on Integrating Nonmonotonicity into Automated Reasoning Systems}, PADDRESS = {Koblenz-Landau, Germany}, ADDRESS = {Budapest, Hungary}, PUBLISHER = {Universit{\"a}t Koblenz-Landau, Institut f{\"u}r Informatik}, MONTH = {September}, SERIES = {Fachberichte Informatik}, VOLUME = {18-96}, YEAR = {1996}, } @INCOLLECTION{Weydert96c, AUTHOR = {Weydert, Emil}, EDITOR = {Fuhrmann, Andr{\'e} and Rott, Hans}, TITLE = {Doxastic Normality Logic: A Qualitative Probabilistic Modal Framework for Defaults and Belief}, BOOKTITLE = {Logic, Action, and Information}, ADDRESS = {New York, USA}, PUBLISHER = {de Gruyter}, ISBN = {3-11-013994-4}, YEAR = {1996}, PAGES = {152--171}, } @PROCEEDINGS{Weydert97a, EDITOR = {Weydert, Emil and Brewka, Gerd and Witteveen, Cees}, TITLE = {Proceedings of the 3rd Dutch/German Workshop on Nonmonotonic Reasoning Techniques and their Applications (DGNMR-97)}, PADDRESS = {Saarbr{\"u}cken, Germany}, ADDRESS = {Saarbr{\"u}cken, Germany}, PUBLISHER = {Max-Planck-Institut f{\"u}r Informatik}, YEAR = {1997}, PAGES = {182}, } @INPROCEEDINGS{Weydert97b, AUTHOR = {Weydert, Emil}, EDITOR = {Weydert, Emil and Brewka, Gerd and Witteveen, Cees}, TITLE = {Qualitative Entropy Maximization - A preliminary report}, BOOKTITLE = {Proceedings of the 3rd Dutch/German Workshop on Nonmonotonic Reasoning Techniques and their Applications (DGNMR-97)}, PADDRESS = {Saarbr{\"u}cken, Germany}, ADDRESS = {Saarbr{\"u}cken, Germany}, PUBLISHER = {Max-Planck-Institut f{\"u}r Informatik}, YEAR = {1997}, PAGES = {63--72}, } @INPROCEEDINGS{Weydert97c, AUTHOR = {Weydert, Emil}, EDITOR = {Gabbay, Dov and Kruse, Rudolf and Nonnengart, Andreas}, TITLE = {Rational Default Quantifier Logic}, BOOKTITLE = {Proceedings of the 1st International Joint Conference on Qualitative and Quantitative Practical Reasoning (ESQARU-FAPR-97)}, PADDRESS = {Heidelberg, Germany}, ADDRESS = {Bad Honnef, Germany}, PUBLISHER = {Springer}, MONTH = {June}, SERIES = {Lecture Notes in Artificial Intelligence}, VOLUME = {1244}, ISBN = {3-540-63095-3}, YEAR = {1997}, PAGES = {589--600}, } @MASTERSTHESIS{Wies2004, AUTHOR = {Wies, Thomas}, TITLE = {Symbolic Shape Analysis}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Master's thesis}, ADDRESS = {Saarbr{\"u}cken, Saarland}, MONTH = {September}, YEAR = {2004}, NOTE = {1.0}, ABSTRACT = {Shape analysis deals with the synthesis of invariants for programs manipulating heap-allocated data structures. Explicit shape analysis algorithms do not scale very well. This work proposes a framework for symbolic shape analysis that addresses this problem. Our contribution is a framework that allows to abstract programs with heap-allocated data symbolically by Boolean programs. For this purpose, we combine abstraction techniques from shape analysis with ideas from predicate abstraction. Our framework is parameterized by a set of abstraction predicates. We propose a class of predicates that can be used to analyze reachability properties for linked data structures. This class may potentially be used for automated abstraction refinement.}, } @INPROCEEDINGS{WiesETAL06FieldConstraintAnalysis, AUTHOR = {Wies, Thomas and Kuncak, Viktor and Lam, Patrick and Podelski, Andreas and Rinard, Martin C.}, EDITOR = {Emerson, E. Allen and Namjoshi, Kedar S.}, TITLE = {Field Constraint Analysis}, BOOKTITLE = {Verification, Model Checking, and Abstract Interpretation : 7th International Conference, VMCAI 2006}, PADDRESS = {Berlin, Germany}, ADDRESS = {Charleston, SC, USA}, PUBLISHER = {Springer}, MONTH = {January}, SERIES = {Lecture Notes in Computer Science}, VOLUME = {3855}, YEAR = {2006}, PAGES = {157--173}, ABSTRACT = { We introduce \emph{field constraint analysis}, a new technique for verifying data structure invariants. A field constraint for a field is a formula specifying a set of objects to which the field can point. Field constraints enable the application of decidable logics to data structures which were originally beyond the scope of these logics, by verifying the backbone of the data structure and then verifying constraints on fields that cross-cut the backbone in arbitrary ways. Previously, such cross-cutting fields could only be verified when they were uniquely determined by the backbone, which significantly limits the range of analyzable data structures. Field constraint analysis permits \emph{non-deterministic} field constraints on cross-cutting fields, which allows the verificiation of invariants for data structures such as skip lists. Non-deterministic field constraints also enable the verification of invariants between data structures, yielding an expressive generalization of static type declarations. The generality of our field constraints requires new techniques, which are orthogonal to the traditional use of structure simulation. We present one such technique and prove its soundness. We have implemented this technique as part of a symbolic shape analysis deployed in the context of the Hob system for verifying data structure consistency. Using this implementation we were able to verify data structures that were previously beyond the reach of similar techniques.}, } @INCOLLECTION{Wu1999, AUTHOR = {Wu, Jinzhao}, EDITOR = {Gao, X-S. and Wang, D.}, TITLE = {First-Order Polynomial based Theorem Proving}, BOOKTITLE = {Mathematics Mechanizations and Applications}, ADDRESS = {San Diego, USA}, PUBLISHER = {Academic Press}, MONTH = {January}, ISBN = {0-12-734760-7}, YEAR = {2000}, PAGES = {273--294}, } @ARTICLE{Wuliu1998, AUTHOR = {Wu, Jinzhao and Liu, Zhuojun}, JOURNAL = {Journal of Automated Reasoning}, TITLE = {Well-Behaved Inference Rules for First-Order Theorem Proving}, NUMBER = {3}, PUBLISHER = {Kluwer}, MONTH = {September}, VOLUME = {21}, ISBN = {0168-7433}, YEAR = {1998}, PAGES = {381--400}, ABSTRACT = { The concept of well-behaved inference rules is developed in first-order polynomial based theorem proving. It is shown that well-behaved inference rules are complete for both the set-of-support strategy and the linear strategy. Two concrete such inference rules are presented, and other two strategies for them are proposed.}, } @INPROCEEDINGS{Wulu1998, AUTHOR = {Wu, Jinzhao and Lu, Mi}, EDITOR = {Li, Zhibin}, TITLE = {CWA in Multi-Valued Logics}, BOOKTITLE = {Proceedings of the 3rd Asian Symposium on Computer Mathematics (ASCM-98)}, ORGANIZATION = {Lanzhou University, the Mathematics Mechanization Research Center (MMRC), and the Japanese Society for Symbolic and Algebraic Computation (JSSAC)}, PADDRESS = {Lanzhou, China}, ADDRESS = {Lanzhou, China}, PUBLISHER = {Lanzhou University}, MONTH = {August}, ISBN = {7-311-01406-9}, YEAR = {1998}, PAGES = {259--270}, } @ARTICLE{Wutanli1998, AUTHOR = {Wu, Jinzhao and Tan, Hongyan and Li, Yongli}, JOURNAL = {Journal of Applied Non-Classical Logics}, TITLE = {An Algebraic Method to Decide the Deduction Problem in Many-Valued Logics}, ADDRESS = {Paris, France}, NUMBER = {4}, PUBLISHER = {Hermes}, MONTH = {December}, VOLUME = {8}, ISBN = {1166-3081}, YEAR = {1998}, PAGES = {353--360}, ABSTRACT = {To decide whether a propositional formula can be deduced from a finite set of formulas in a given many-valued logic system, we only need to decide whether a polynomial vanishes on an algebraic variety. By using Wu's method, we present an algorithm for this deduction problem.}, } @ARTICLE{XiaYang02, AUTHOR = {Xia, Bican and Yang, Lu}, JOURNAL = {Journal of Symbolic Computation}, TITLE = {An Algorithm for Isolating the Real Solutions of Semi-algebraic Systems}, ADDRESS = {Orlando, USA}, NUMBER = {5}, PUBLISHER = {Academic Press}, MONTH = {November}, VOLUME = {34}, YEAR = {2002}, PAGES = {461--477}, } @INPROCEEDINGS{Yoshida94, AUTHOR = {Yoshida, Tetsuja and Bundy, Alan and Green, Ian and Walsh, Toby and Basin, David A.}, EDITOR = {Cohn, Tony}, TITLE = {Coloured Rippling: An Extension of a Theorem Proving Heuristic}, BOOKTITLE = {Proceedings of the 12th European Conference on Artificial Intelligence (ECAI'94)}, PADDRESS = {?}, ADDRESS = {Amsterdam, Netherlands}, PUBLISHER = {Wiley}, YEAR = {1994}, PAGES = {85--89}, } @PHDTHESIS{ZeyerDiss1997, AUTHOR = {Zeyer, J{\"o}rg}, TITLE = {Eine Beobachtungs-Logik f{\"u}r modulare Sprachen}, SCHOOL = {Universit{\"a}t des Saarlandes}, TYPE = {Doctoral dissertation}, YEAR = {1997}, }