This volume contains revised refereed versions of the best papers presented during the CSL '94 conference, held in Kazimierz, Poland in September 1994; CSL '94 is the eighth event in the series of workshops held for the third time as the Annual Conference of the European Association for Computer Science Logic.
The 38 papers presented were selected from a total of 151 submissions. All important aspects of the methods of mathematical logic in computer science are addressed: lambda calculus, proof theory, finite model theory, logic programming, semantics, category theory, and other logical systems. Together, these papers give a representative snapshot of the area of logical foundations of computer science.

Formal specifications were first used in the description of program ming languages because of the central role that languages and their compilers play in causing a machine to perform the computations required by a programmer. In a relatively short time, specification notations have found their place in industry and are used for the description of a wide variety of software and hardware systems. A formal method - like VDM - must offer a mathematically-based specification language. On this language rests the other key element of the formal method: the ability to reason about a specification. Proofs can be empioyed in reasoning about the potential behaviour of a system and in the process of showing that the design satisfies the specification. The existence of a formal specification is a prerequisite for the use of proofs; but this prerequisite is not in itself sufficient. Both proofs and programs are large formal texts. Would-be proofs may therefore contain errors in the same way as code. During the difficult but inevitable process of revising specifications and devel opments, ensuring consistency is a major challenge. It is therefore evident that another requirement - for the successful use of proof techniques in the development of systems from formal descriptions - is the availability of software tools which support the manipu lation of large bodies of formulae and help the user in the design of the proofs themselves."

This volume contains the proceedings of the 15th International Conference on Application and Theory of Petri Nets, held at Zaragoza, Spain in June 1994. The annual Petri net conferences are usually visited by some 150 - 200 Petri net experts coming from academia and industry all over the world.
The 28 full papers were selected out of in total 85 submissions from 18 countries. Together with the 3 invited contributions, these papers give a state-of-the-art report on all relevant aspects of Petri nets.

Techniques for reasoning about actions an change in the physical world is one of the classical research topics in artificial intelligence. It is motivated by the needs of autonomous robots which must be able to anticipate their immediate future, to plan their future actions, and to figure out what went wrong in case of problems. It is also motivated by the needs of common-sense reasoning for example in the understanding of natural language texts, where processes and change over time is an ever-present phenomenon. The same set of problems arises in several other areas of computing such as in conceptual modelling for data bases, and in the rapidly growing area of intelligent control. The present research monograph presents and uses a novel methodology for reasoning about actions and change. Traditional research contributions have proposed new logic variants which were only supported by episodical examples. THe work described here uses a systematic methodology for identifying the exact range of applicability of a given logic. For a number of previously proposed logics, as well as for some new ones, the present work characterizes exactly the class where it does not. This book will be a necessary source of reference for researchers in knowledge representation, cognitive robotics, and intelligent control in the years to come. Particularly because of its emphasis on a strict and systematic methodology, it can also be recommended as a textbook for graduate university courses in these areas.

This volume presents the proceedings of the Computer Science Logic Workshop CSL '92, held in Pisa, Italy, in September/October 1992. CSL '92 was the sixth of the series and the first one held as Annual Conference of the European Association for Computer Science Logic (EACSL). Full versions of the workshop contributions were collected after their presentation and reviewed. On the basis of 58 reviews, 26 papers were selected for publication, and appear here in revised final form. Topics covered in the volume include: Turing machines, linear logic, logic of proofs, optimization problems, lambda calculus, fixpoint logic, NP-completeness, resolution, transition system semantics, higher order partial functions, evolving algebras, functional logic programming, inductive definability, semantics of C, classes for a functional language, NP-optimization problems, theory of types and names, sconing and relators, 3-satisfiability, Kleene's slash, negation-complete logic programs, polynomial-time oracle machines, and monadic second-order properties.

This volume contains work on the decision problem done in Kazan (Russia), Tallinn (Estonia), and Vienna (Austria). The authors met several times to discuss and exchange their results and finally decided to write this monograph together. Besides a unified treatment of previously published results there are many new results first presented in this volume. The monograph opens with an introduction and a chapter on terminology, followed by chapters on: - Semantic clash resolution as decision procedure, - Completeness of ordering refinements, - Semantic tree based resolution variants, - Deciding the class K by an ordering refinement, - A resolution based method for building finite models. A final chapter on applications completes the volume.

The lambda calculus was developed in the 1930s by Alonzo Church. The calculus turned out to be an interesting model of computation and became theprototype for untyped functional programming languages. Operational and denotational semantics for the calculus served as examples for otherprogramming languages. In typed lambda calculi, lambda terms are classified according to their applicative behavior. In the 1960s it was discovered that the types of typed lambda calculi are in fact appearances of logical propositions. Thus there are two possible views of typed lambda calculi: - as models of computation, where terms are viewed as programs in a typed programming language; - as logical theories, where the types are viewed as propositions and the terms as proofs. The practical spin-off from these studies are: - functional programming languages which are mathematically more succinct than imperative programs; - systems for automated proof checking based on lambda caluli. This volume is the proceedings of TLCA '93, the first international conference on Typed Lambda Calculi and Applications, organized by the Department of Philosophy of Utrecht University. It includes29 papers selected from 51 submissions.

This volume presents the proceedings of the workshop CSL '91 (Computer Science Logic) held at the University of Berne, Switzerland, October 7-11, 1991. This was the fifth in a series of annual workshops on computer sciencelogic (the first four are recorded in LNCS volumes 329, 385, 440, and 533). The volume contains 33 invited and selected papers on a variety of logical topics in computer science, including abstract datatypes, bounded theories, complexity results, cut elimination, denotational semantics, infinitary queries, Kleene algebra with recursion, minimal proofs, normal forms in infinite-valued logic, ordinal processes, persistent Petri nets, plausibility logic, program synthesis systems, quantifier hierarchies, semantics of modularization, stable logic, term rewriting systems, termination of logic programs, transitive closure logic, variants of resolution, and many others.

This volume contains papers presented at the second International Workshop on Word Equations and Related Topics (IWWERT '91), held at the University ofRouen in October 1991. The papers are on the following topics: general solution of word equations, conjugacy in free inverse monoids, general A- and AX-unification via optimized combination procedures, wordequations with two variables, a conjecture about conjugacy in free groups, acase of termination for associative unification, theorem proving by combinatorial optimization, solving string equations with constant restriction, LOP (toward a new implementation of Makanin's algorithm), word unification and transformation of generalizedequations, unification in the combination of disjoint theories, on the subsets of rank two in a free monoid (a fast decision algorithm), and a solution of the complement problem in associative-commutative theories.

This volume contains the proceedings of JELIA '92, les Journ es Europ ennes sur la Logique en Intelligence Artificielle, or the Third European Workshop on Logics in Artificial Intelligence. The volume contains 2 invited addresses and 21 selected papers covering such topics as: - Logical foundations of logic programming and knowledge-based systems, - Automated theorem proving, - Partial and dynamic logics, - Systems of nonmonotonic reasoning, - Temporal and epistemic logics, - Belief revision. One invited paper, by D. Vakarelov, is on arrow logics, i.e., modal logics for representing graph information. The other, by L.M. Pereira, J.J. Alferes, and J.N. Apar cio, is on default theory for well founded semantics with explicit negation.

This volume contains the proceedings of the 14th International Conference onApplication and Theory of Petri Nets. The aim of the Petri net conferences is to create a forum for discussing progress in the application and theory of Petri nets. Typically, the conferences have 150-200 participants, one third of whom come from industry, while the rest are from universities and research institutes. The volume includes three invited papers, "Modeling and enactment of workflow systems" (C.A. Ellis, G.J. Nutt), "Interleaving functional and performance structural analysis of net models" (M. Silva), and "FSPNs: fluid stochastic Petri nets" (K.S. Trivedi, V.G. Kulkarni), together with 26 full papers (selected from 102 submissions) and 6 project papers.

Logic programming enjoys a privileged position. It is firmly rooted in mathematical logic, yet it is also immensely practical, as a growing number of users in universities, research institutes, and industry are realizing. Logic programming languages, specifically Prolog, have turned out to be ideal as prototyping and application development languages. This volume presents the proceedings of the Second Logic Programming Summer School, LPSS'92. The First Logic Programming Summer School, LPSS '90, addressed the theoretical foundations of logic programming. This volume focuses onthe relationship between theory and practice, and on practical applications. The introduction to the volume is by R. Kowalski, one of the pioneers in the field. The following papers are organized into sections on constraint logic programming, deductive databases and expert systems, processing of natural and formal languages, software engineering, and education.

This volume comprises the proceedings of the First All-Berlin Workshop on Nonclassical Logics and Information Processing, held at the Free University of Berlin, November 9-10, 1990. The scope of the ten papers in the volume is broad, covering various different subfields of logic - particularly nonclassical logic - and its applications in artificial intelligence. The papers are grouped according to the four major topics that emerged at the meeting: modal systems, logic programming, nonmonotonic logics, and proof theory. The classification is only a rough guide since the four areas overlap considerably.

This volume contains lectures and papers delivered at Meta 92, the Third International Workshop on Metaprogramming in Logic, held in Uppsala, Sweden, June 1992. The topics covered include foundations of metaprogramming in logic, proposals for metaprogramming languages, techniques for knowledgerepresentation and belief systems, and program transformation and analysis in logic. Particular topics include belief revision systems, intensionaldeduction, belief systems and metaprogramming, principles of partial deduction, termination in logic programs, semantics of the "vanilla" metainterpreter, a complete resolution method for metaprogramming, semanticsof "demo," hierarchical metalogics, the naming relation in metalevel systems, modules, reflective agents, compiler optimizations, metalogic and object-oriented facilities, parallel logic languages, the use of metaprogramming for legal reasoning, representing objects and inheritance, transformation of normal programs, negation in automatically generated logic programs, reordering of literals in deductive databases, abstract interpretations, and interarguments in constraint logic programs.

This book principally concerns the rapidly growing area of what might be termed "Logical Complexity Theory": the study of bounded arithmetic, propositional proof systems, length of proof, and similar themes, and the relations of these topics to computational complexity theory. Issuing from a two-year international collaboration, the book contains articles concerning the existence of the most general unifier, a special case of Kreisel's conjecture on length-of-proof, propositional logic proof size, a new alternating logtime algorithm for boolean formula evaluation and relation to branching programs, interpretability between fragments of arithmetic, feasible interpretability, provability logic, open induction, Herbrand-type theorems, isomorphism between first and second order bounded arithmetics, forcing techniques in bounded arithmetic, and ordinal arithmetic in *L *D o. Also included is an extended abstract of J.P. Ressayre's new approach concerning the model completeness of the theory of real closed exponential fields. Additional features of the book include the transcription and translation of a recently discovered 1956 letter from Kurt Godel to J. von Neumann, asking about a polynomial time algorithm for the proof in k-symbols of predicate calculus formulas (equivalent to the P-NP question); and an open problem list consisting of seven fundamental and 39 technical questions contributed by many researchers, together with a bibliography of relevant references. This scholarly work will interest mathematical logicians, proof and recursion theorists, and researchers in computational complexity.

This volume contains papers presented at the first international workshop onword equations and related topics held at the University of T}bingen in October 1990. Word equations, the central topic of this annual workshop, lieat the intersection of several important areas of computer science, suchas unification theory, combinatorics on words, list processing, and constraint logic programming. The workshop is a forum where researchers fromthese different domains may present and discuss results and ideas, thereby supporting interaction and cross-fertilization between theoretical questions and practical applications. The volume collects papers which: - contain new and relevant results, - describe a new approach to a subject, or - give a survey of main developments in an area. Papers cover investigations on free groups, associative unification and Makanin's algorithm to decide the solvability of equations in free semigroups, general unification theory and its relationship to algebra and model theory, Thue systems, and finitely presented groups.

This book presents state-of-the-art research results in the area of formal methods for real-time and fault-tolerant systems. The papers consider problems and solutions in safety-critical system design and examine how wellthe use of formal techniques for design, analysis and verification serves in relating theory to practical realities. The book contains papers on real-time and fault-tolerance issues. Formal logic, process algebra, and action/event models are applied: - to specify and model qualitative and quantitative real-time and fault-tolerant behavior, - to analyze timeliness requirements and consequences of faulthypotheses, - to verify protocols and program code, - to formulate formal frameworks for development of real-time and fault-tolerant systems, - to formulate semantics of languages. The integration and cross-fertilization of real-time and fault-tolerance issues have brought newinsights in recent years, and these are presented in this book.

This proceedings volume contains a selection of revised and extended papers presented at the Second International Workshop on Nonmonotonic and InductiveLogic, NIL '91, which took place at Reinhardsbrunn Castle, December 2-6, 1991. The volume opens with an extended version of a tutorial on nonmonotonic logic by G. Brewka, J. Dix, and K. Konolige. Fifteen selected papers follow, on a variety of topics. The majority of papers belong either to the area of nonmonotonic reasoning or to the field of inductive inference, but some papers integrate research from both areas. The first workshop in this series was held at the University of Karlsruhe in December 1990 and its proceedings were published as Lecture Notes in Artificial Intelligence Volume 543. The series of workshops was made possible by financial support from Volkswagen Stiftung, Hannover. This workshop was also supported by IBM Deutschland GmbH and Siemens AG.

This volume contains the proceedings of the second workshop on Computer Aided Verification, held at DIMACS, Rutgers University, June 18-21, 1990. Itfeatures theoretical results that lead to new or more powerful verification methods. Among these are advances in the use of binary decision diagrams, dense time, reductions based upon partial order representations and proof-checking in controller verification. The motivation for holding a workshop on computer aided verification was to bring together work on effective algorithms or methodologies for formal verification - as distinguished, say, from attributes of logics or formal languages. The considerable interest generated by the first workshop, held in Grenoble, June 1989 (see LNCS 407), prompted this second meeting. The general focus of this volume is on the problem of making formal verification feasible for various models of computation. Specific emphasis is on models associated with distributed programs, protocols, and digital circuits. The general test of algorithm feasibility is to embed it into a verification tool, and exercise that tool on realistic examples: the workshop included sessionsfor the demonstration of new verification tools.

The workshop Computer Science Logic '90 was held at the Max-Planck-Haus in Heidelberg, Germany, October 1-5, 1990. It was the fourth in a series of worskhops, following CSL '89 at the University of Kaiserslautern (see LNCS 440), CSL '88 at the University of Duisberg (see LNCS 385), and CSL '87 at the University of Karlsruhe (see LNCS 329). This volume contains 24 papers, chosen by means of a review procedure from the 35 papers presented at the workshop, some of which were invited and some selected from a total of 89 submissions. The papers cover a wide range of topics arising from the applications of logic to computer science.

This volume presents the papers selected for the Symposium Logic at Tver '92, held at Sokol, near Tver, Russia in July 1992. It is the second in a series of international symposia on logical foundations of computer science held in Russia. The meeting is a joint effort of scholars from both the former Soviet Union and the West, and indicates a new era of international cooperation. Sponsors of the meeting include: the Association for Computing Machinery, the Association for Symbolic Logic, andthe Committee on Mathematical Foundations of Computer Science of IEEE. The book is a unique source of information on the state of computer science research in the former Soviet Union and presents important discoveries in the area of logical foundations of computer science.

This volume contains the papers which have been accepted for presentation atthe Third International Symposium on Programming Language Implementation andLogic Programming (PLILP '91) held in Passau, Germany, August 26-28, 1991. The aim of the symposium was to explore new declarative concepts, methods and techniques relevant for the implementation of all kinds of programming languages, whether algorithmic or declarative ones. The intention was to gather researchers from the fields of algorithmic programming languages as well as logic, functional and object-oriented programming. This volume contains the two invited talks given at the symposium by H. Ait-Kaci and D.B. MacQueen, 32 selected papers, and abstracts of several system demonstrations. The proceedings of PLILP '88 and PLILP '90 are available as Lecture Notes in Computer Science Volumes 348 and 456.

These proceedings contain research and survey papers from many subfields of recursion theory, with emphasis on degree theory, in particular the development of frameworks for current techniques in this field. Other topics covered include computational complexity theory, generalized recursion theory, proof theoretic questions in recursion theory, and recursive mathematics.

Attribute grammars have shown themselves to be a useful formalism for specifying the syntax and the static semantics of programming languages. They are also useful for implementing syntax-directed editors, compilers, translator writing systems and compiler generators, and any application that has a strong syntactic base. However, no textbooks are available that cover the entire field. To redress this imbalance, anInternational Summer School on Attribute Grammars, Applications and Systems was held in Prague, Czechoslovakia in June 1991. The course aimed at teaching the state of the art in attribute grammars, and their relation to other language specification methods. This volume presents the proceedings of the school. The papers are well suited for self-study, and a selection of them can be used for introductory courses in attribute grammars.

The courses given at the 1st C.I.M.E. Summer School of 1988 dealt with the main areas on the borderline between applied logic and theoretical computer science. These courses are recorded here in five expository papers: S. Homer: The Isomorphism Conjecture and its Generalization.- A. Nerode: Some Lectures on Intuitionistic Logic.- R.A. Platek: Making Computers Safe for the World. An Introduction to Proofs of Programs. Part I. - G.E. Sacks: Prolog Programming.- A. Scedrov: A Guide to Polymorphic Types.