Electronic Notes In Theoretical Computer Science Series Research Articles

Preface: Volume 89, Issue 2

ForewordThis volume contains the proceedings of the Third International Workshop on Run-time Verification (RV '03). RV '03 was held on July 13, 2003, as a satellite workshop of the International Conference of Computer-Aided Verification (CAV '03). The first two workshops in this series were also held as satellite workshops of CAV; RV '01 was held in Paris in July 2001, and RV '02 was held in Copenhagen in July 2002.The purpose of this series of workshops has been to bring together researchers and practitioners, interested in various aspects related to the dynamic analysis of software and systems, with respect to formally specified correctness requirements. Run-time verification aims to provide a “lightweight” complement to traditional verification methods like model checking and theorem proving, by analysing an actual implementation with respect to the reduced correctness obligations of certifying the correctness of a single execution. Despite the weaker guarantees, run-time verification improves upon other more ad-hoc approaches in monitoring, by providing formal proofs.The papers selected for this year's workshop cover a wide range of topics related to runtime verification, including designing efficient and optimal verification algorithms, techniques for instrumenting programs at the source or object code/byte code level to observe program execution, developing specification languages for monitors, dynamic program analysis, and formally proving the correctness of monitoring systems. This volume includes these papers and the abstract of the Invited Presentation by the Invited Presentation by Aloysius K. Mok (University of Texas at Austin). The volume will be published in the Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URL http://www.elsevier.nl/locate/entcs.We would like to thank the Program Committee members and their reviewers, who did an excellent job evaluating the submissions and shaping the program of the workshop. We are grateful to the Steering Committee for helpful guidance and support. Special thanks go to Al Mok for agreeing to be the Invited Speaker. Thanks to the CAV '03 co-Chairs: Warren A. Hunt, Jr. (University of Texas at Austin) and Fabio Somenzi (University of Colorado at Boulder) for the opportunity to continue the tradition of having the RV workshops as CAV satellites. July 1, 2003Oleg SokolskyMahesh Viswanathan Program CommitteeSaddek BensalemVERIMAG LaboratoryRance CleavelandState University of New York at Stony BrookAnn GatesUniversity of Texas, El PasoPatrice GodefroidBell LaboratoriesGerard HolzmannNASA/JPL Laboratory for Reliable SoftwareSusan HorwitzUniversity of Wisconsin, MadisonMichael MoellerUniversity of OldenburgAloysius K. MokUniversity of Texas, AustinHenny SipmaStanford UniversityOleg SokolskyUniversity of PennsylvaniaScott StollerState University of New York at Stony BrookMahesh ViswanathanUniversity of Illinois at Urbana-ChampaignSergio YovineVERIMAG LaboratoryLenore ZuckNew York University Steering CommitteeKlaus HavelundNASA Ames Research Center - Kestrel TechnologyInsup LeeUniversity of PennsylvaniaGrigore RosuUniversity of Illinois at Urbana-Champaign

Preface: Volume 82, Issue 8

First Workshop on Object Oriented DevelopmentsThis volume contains the Proceedings of the First Workshop on Object Oriented Developments (WOOD'2003). The Workshop was held in Warsaw, Poland on April 13, 2003, as a satellite event to ETAPS'2003.Object-oriented programming languages have long been the subject of extensive foundational and applied research in a wide range of fields, including semantics, type theory, program verification and program development. More recently, object-oriented programming has emerged as an effective paradigm for structuring, composing and coordinating concurrent, distributed, and mobile code. The workshop provided a forum for discussion about theoretical work on object-oriented models and type systems, as well as presentation of experience reports on, and novel techniques for, program analysis and verification.The volume includes two invited presentations, and five papers selected for publication by the following Program Committee Members: •Viviana Bono (University of Torino, Italy)•Michele Bugliesi (University of Venezia, Italy)•Giuseppe Castagna(Ecole Normale Superieure, Paris, France)•Adriana Compagnoni(Stevens Institute of Technology, USA)•Kathleen Fisher(AT&T Labs, USA)•Matthew Flatt(University of Utah, USA)•Julian Rathke(University of Sussex, UK)•Christopher Stone(Harvey Mudd College, USA))This volume will be published as Volume 82 in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URLhttp://www.elsevier.nl/locate/entcsWe would like to thank all who contributed to the success of WOOD2003:the participants, the invited speakers Kim B. Bruce and Vladimiro Sassone, the authors, the PC members, the ETAPS organisers and the ENTCS editors. Special thanks to Damian Niwinski for his help with the organization of the Workshop, to Michael Mislove and Elsevier Publishers for making it possible to include our proceedings in Electronic Notes in Theoretical Computer Science and to Warsaw University for printing the hard copy of our proceedings. June 15, 2003Viviana Bono and Michele Bugliesi

Preface: Volume 85, Issue 7

Preface: Volume 85, Issue 7

Preface: Volume 82, Issue 5

SC 2003: Workshop on Software Composition Affiliated with ETAPS 2003Warsaw, Poland, April 6th, 2003This volume contains the Proceedings of the Second Workshop on Software Composition (SC 2003). The Workshop has been held in Warsaw, Poland on April 6th, 2003, as a satellite event of ETAPS 2003.The aim of the SC Workshop is to collect different approaches and experiences in the domain of software composition. Component-based approaches to produce software from smaller units attract increasing attention of both research and industry. The rational behind this trend is in the promise of reuse. This is the idea to produce software by “plug & play” components which already exist or are produced by different external vendors. Components and software composition are considered to be a new way to overcome the remaining problems (e.g. reusability, deal with complexity) still not solved by the object-oriented paradigm.In this context, the SC workshop collects different approaches and experiences to explore and overcome the gap between promise and reality. The goal is to demystify these new approaches based on components and instead elaborate the real advantages, problems and challenges.The papers in this issue have been reviewed by the following Program Committee Members: •Uwe Assmann, Linköpings Universitet, Sweden, http://www.ida.liu.se/~uweas•Elke Pulvermueller, Universitaet Karlsruhe, Germany•Isabelle Borne, Université de Bretagne-Sud, France•Noury Bouraqadi, Ecole des Mines de Douai, France•Pierre Cointe, Ecole des Mines de Nantes, France•Zoltan Laslo, Budapest University of Technology and Economics, Hungary http://www.fsz.bme.hu/staff/laszlo/•Welf Loewe, Växjö Universitet, Sweden http://www.masda.vxu.se/~wlo/index.en.htm•M. Awais Rashid, Lancaster University, UK http://www.comp.lancs.ac.uk/computing/users/marash•Benedikt Schulz, Forschungszentrum Informatik Karlsruhe, Germany•Mario Suedholdt, École des Mines de Nantes, France http://www.emn.fr/sudholt/•Bedir Tekinerdogan, University of Twente, The Netherlands•Arnd Poetzsch-Heffter, Universität Kaiserslautern, Germany http://softech.informatik.uni-kl.de/mitarbeiter/poetzsch.htmlThis volume will be published in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at URL :http://www.elsevier.nl/locate/entcshttp://math.tulane.edu/~entcsWe thank all persons contributing to the success of SC2003: the authors, participants, PC Members, the ETAPS organisers and the ENTCS editors.This workshop was partially funded by the EC in the context of the project EASYCOMP (IST 1999-14191).

Preface: Volume 68, Issue 6

INFINITY 2002, the 4th International Workshop on Verification of Infinite-State Systems, was held as a satellite workshop of CONCUR 2002 (the 13th International Conference on Concurrency Theory) in Brno, Czech Republic, on August 24, 2002. The aim of the workshop is to provide a forum for researchers interested in the development of mathematical techniques for the analysis and verification of systems with infinitely many states. The topics of INFINITY 2002 included the following: techniques for modeling and analysis of infinite-state systems, equivalence-checking and model-checking with infinite-state systems, parameterized systems, calculi for mobility and security, finite-state abstractions of infinite-state systems.The volume consists of six contributed papers selected by the INFINITY 2002 programme committee. The papers were reviewed by the program committee consisting, besides editors, of Parosh Abdulla(Uppsala (SE))Julian Bradfield(Edinburgh (UK))Didier Caucal(Irisa (F))Hubert Comon(LSV Cachan (F))Giorgio Delzanno(Genova (I))Yoram Hirshfeld(Tel-Aviv (Israel))Denis Lugiez(Marseille (F))Bernhard Steffen(Dortmund (D))P.S. Thiagarajan(Chennai (India))Moshe Vardi(Rice (USA))The programme of INFINITY 2002 was further enriched by an invited talk given by Colin Stirling, and by four short presentations of work in progress.This volume will be published as volume 68(6) in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URL http://www.elsevier.nl/locate/entcsWe are very grateful to the CONCUR 2002 Organizing Committee for arranging all local affairs, and to Michael Mislove, the managing editor of ENTCS, for providing the opportunity to publish the INFINITY 2002 proceedings in the ENTCS series.December 9, 2002 Antonin Kucera, Richard Mayr

Preface: Volume 65, Issue 3

ForewordThis is the second edition of the Workshop on Language Descriptions, Tools, and Applications (LDTA). Theme of this workshop is the description of (programming) languages and the development and/or generation of tools for these languages based on formal descriptions. The aim of this workshop is to bring together researchers from academia and industry interested in the formal definition of languages, and the use of these definitions for the derivation of tools and software applications (e.g., interactive transformation tools, software renovation tools, application generators). The contributions for this workshop are based on all kinds and styles of formal language definition including attribute grammars, algebraic approaches, action semantics, operational semantics, and denotational semantics. Many aspects of the definition of languages, and the derivation of tools and applications are independent of the actual formalism used. The workshop also welcomes contributions to compare formalisms or to discuss the benefits and drawbacks of specific formalisms.The LDTA 2002 program consists of 6 regular peer-reviewed papers, which were selected from 14 submissions, one invited talk by Charles Consel on “Domain-Specific Languages: What, Why, How”, and 4 invited tool demonstrations. The selected papers cover a broad range of themes like: applying rewriting strategies to build interpreters, program slicing based on XML, application of aspect oriented programming and XML, multi-lingual bibliography tooling, and incremental attribute evaluators. The tool demonstrations are concerned with presentations of the new ELAN environment, an environment for action semantics, the Grammar Deployment Kit (GDK), and the ELI system.This volume will be published as volume 65-3 in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URL http://www.elsevier.nl/locate/entcsWe would like to thank the program committee members for their help in evaluating the papers and making a scientifically interesting selection. Furthermore, we would like to thank the ETAPS organizing committee for taking care of the local organization of our workshop. We are very pleased that these proceedings are published in the Electronic Notes in Theoretical Computer Science (ENTCS) by Elsevier, which increases the visibility of the LDTA workshop.Organizing CommitteeGorel Hedin(Lund Institute of Technology, Lund, Sweden)Marjan Mernik(University of Maribor, Maribor, Slovenia)Didier Parigot(INRIA, Sophia Antipolis, France)Program CommitteeMark van den Brand(CWI, Amsterdam, The Netherlands)Barrett R. Bryant(University of Alabama, Birmingham, USA)Katsuhiko Gondow(JAIST, Japan)Ralf Lämmel(Vrije Universiteit Amsterdam, The Netherlands)Jan Heering(CWI, Amsterdam, The Netherlands)Oege de Moor(Oxford University Computing Laboratory, Great Britain)Pierre-Etienne Moreau(INRIA/LORIA, Nancy, France)Peter D. Mosses(BRICS, Aarhus, Denmark)Joao Saraiva(University of Minho, Portugal)David Watt(University of Glasgow, Great Britain)

Preface: Volume 65, Issue 6

This volume contains the Proceedings of the First Workshop on the Theory and Practice of Timed Systems (TPTS'2002). The Workshop was held in Grenoble, France on April 6 and 7, 2002, as satellite event to ETAPS'2002.The study of time-dependent behavior is treated currently under different titles by different communities. Classical problems of manufacturing scheduling, for example, are considered as part of operation research and industrial engineering. Similar but different scheduling problems are encountered in the research on real-time operating systems. People who are interested in semantics, verification or performance analysis are working on models such as timed automata, timed Petri nets or max-plus algebra. Electrical engineers have to consider propagation delays in their circuits and designer of embedded controllers have to take into account the time it takes for the controller to compute its reaction after sampling the environment. The unifying theme underlying all these apparently different domains is that they treat systems whose behavior depends upon combinations of logical and temporal constraints, i.e. constraints on the distance between the occurrences of two events.The workshop goal is to promote the study of fundamental and practical aspects of timed systems. The three major axes of interest are listed below: Foundations and semantics: contributions to a better theoretical foundations for timed systems and timed formal languages as well as a comparison between different models used by different communities (timed automata, timed Petri nets, max-plus algebra, etc.).Algorithms and tools: new algorithms and data-structures for analyzing timed systems and resolving temporal constraints. are needed in order to push timing technology into the real world.Applications: adaptation and specialization of timing technology to the modeling and analysis of certain types of application domains in which timing plays an important role (real-time software, hardware circuits and problems of scheduling in manufacturing or telecommunication).The papers in this volume were reviewed by the program committee consisting of Rajeev Alur(U. Penn, Philadelphia)Eugene Asarin(Verimag, Grenoble)Ahmed Bouajjani(LIAFA, Paris)Jordi Cortadella(U. Catalunya, Barcelona)Sebastian Engell(U. of Dortmund)Tom Henzinger(U. California, Berkeley)Bengt Jonsson(U. of Uppsala)Kim Larsen(U. of Aalborg)Insup Lee(U. Penn, Philadelphia)Oded Maler(Verimag, Grenoble)Chris Myers(U. Utah, Salt Lake City)Peter Niebert(U. Provence, Marseille)Antoine Petit(ENS, Cachan)Paul Petterson(U. of Uppsala)Amir Pnueli(Weizmann Institute, Rehovot)Alex Rabinovich(U. of Tel-Aviv)Jean-Francois Raskin(Free University, Brussels)Karem Sakallah(U. Michigan, Ann Arbor)Ken Stevens(Intel, Hillsboro)Wang Yi(U. of Uppsala)Sergio Yovine(Verimag, Grenoble)This volume will be published as volume 65, issue 6 in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URLMarch 18, 2002 Eugene Asarin, Oded Maler, Sergio Yovine

Preface: Volume 52, Issue 3

A large class of systems can be specified and verified by abstracting away from the temporal aspects. This is the class of systems where time affects the performance but not the functional behaviour. In time-critical systems, instead, time issues become essential. Their correctness depends not only on which actions a system can perform but also on their execution time. Due to their importance, time-critical systems have attracted the attention of a considerable number of computer scientists from various research areas.This volume contains the Proceedings of the 2nd International Workshop on Models for Time-Critical Systems (MTCS 2001); MTCS 2001 was held on 25 August 2001 as one of five satellite workshops co-located with the 12th International Conference on Concurrency Theory (CONCUR 2001), held in Aalborg (Denmark) 21-24 August 2001.The first workshop, MTCS 2000, was held in State College (Pennsylvania, USA) on 26 August 2000, co-chaired by Flavio Corradini and Paola Inverardi. As for MTCS 2000, the objectives of MTCS 2001 were (i) to validate the more promising proposals on models for time-critical systems, ranging from theory to practice and (ii) to promote interaction between different research areas in the field of time-critical systems. Despite its focus on time-critical systems, MTCS 2001 was also open for more general time-related issues.The papers in this volume were selected for presentation by the Program Committee from submissions received in response to a Call for Papers. This volume will be published as volume 52 in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URL http://www.elsevier.nl/locate/entcsThe volume includes the contribution by the Invited Speaker Jos Baeten (Eindhoven University of Technology).We would like to thank Kim G. Larsen and Mogens Nielsen (CONCUR 2001 Conference Chairs) and Hans Huttel (Satellite Workshops Chair) for the opportunity they gave us to organize MTCS 2001 and for their support. Many thanks are due to Jos Baeten (Invited Speaker), and to the members of the Program Committee as well as their sub-referees for their accurate work. We would also like to thank Michael Mislove for his help during the proceedings editorial process and to BRICS for the publication of the preliminary proceedings.The papers in this volume were reviewed by the program committee consisting of Rajeev Alur(USA)Jos Baeten(NL)Frank de Boer(NL)Flavio Corradini(IT)Paola Inverardi(IT)Jeff Kramer(UK)Gerald Luettgen(UK)Jeff Magee(UK)Andrea Maggiolo-Schettini(IT)Bran Selic(CA)Joseph Sifakis(FR)Walter Vogler(DE)A printed version of the current volume is distributed to the participants at the workshop in Aalborg.May 7, 2002Flavio Corradini, Walter Vogler

Preface: Volume 65, Issue 4

This volume contains the Proceedings of the First Workshop on Software Composition (SC 2002). The Workshop has been held in Grenoble, France on April 7th, 2001, as a satellite event of ETAPS 2002.The aim of the SC Workshop is to collect different approaches and experiences in the domain of software composition. Component-based approaches to produce software from smaller units attract increasing attention of both research and industry. The rational behind this trend is in the promise of reuse. This is the idea to produce software by “plug & play” components which already exist or are produced by different external vendors. Components and software composition are considered to be a new way to overcome the remaining problems (e.g. reusability, deal with complexity) still not solved by the object-oriented paradigm.In this context, the SC workshop collects different approaches and experiences to explore and overcome the gap between promise and reality. The goal is to demystify these new approaches based on components and instead elaborate the real advantages, problems and challenges.The papers in this issue have been reviewed by the following Program Committee Members: •Uwe Assmann, Linköpings Universitet, Sweden•Pierre Cointe, Ecole des Mines de Nantes, France•Isabelle Borne, Ecole des Mines de Nantes, France•Noury Bouraqadi, Ecole des Mines de Douai, France•Serge Demeyer, University of Antwerp, Belgium•Zoltan Laszlo, Budapest University of Technology and Economics, Hungary•Welf Loewe, Universitaet Karlsruhe, Germany•Mira Mezini, Darmstadt University of Technology, Germany•Arnd Poetzsch-Heffter, FernUniversitaet Hagen,•Elke Pulvermueller, Universitaet Karlsruhe, Germany•M. Awais Rashid, Lancaster University, UK•Benedikt Schulz, Forschungszentrum Informatik Karlsruhe, Germany•Andreas Speck, Intershop Research, Jena, Germany•Mario Südholt, Ecole des Mines de Nantes, France•Bedir Tekinerdogan, University of Twente, The NetherlandsThis volume will be published in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at URL: http://www.elsevier.nl/locate/entcshttp://math.tulane.edu/~entcsWe thank all persons contributing to the success of SC2002: the authors, participants, PC Members, the ETAPS organisers and the ENTCS editors.This workshop was partially funded by the EC in the context of the project EASYCOMP (IST 1999-14191).

Preface: Volume 59, Issue 4

ForewordThis volume contains the Proceedings of the Second International Workshop on Rule-Based Programming (RULE2001). The Workshop was held in Firenze, Italy on September 4, 2001, as satellite event to PLI2001.This is the second edition of the International Workshop on Rule-Based Programming (RULE'2001). We aim with this workshop at a fruitful cross fertilization of the theoretical foundations of rule-based programming with practical applications and implementation of rule-based systems. We are very pleased with the broad range of papers: quite a number of very theoretical ones upto papers describing a system and a paper describing a comparison between a number of rule-based systems to tackle a bio-medical problem.Rule-based programming began with AI rule-based systems in the seventies. This paradigm is inherent in Prolog and has been used in program-manipulation systems like Refine. Indeed, the rewriting concept appears throughout computer science, from its theoretical foundations to very practical implementations. Extreme examples include the mail system in Unix which uses rules in order to rewrite mail addresses to canonical forms and the transition rules describing the behaviour of tree automata. Rewriting is used in semantics in order to describe the meaning of programming languages, as well as in program transformations like the re-engineering of Cobol programs. It is used to compute, implicitly or explicitly, as in Mathematica or OBJ, but also to perform deduction when using inference rules to describe a logic, theorem prover or constraint solver. Last, but not least, this approach is central to systems that raise the notion of rule to an explicit first class object, like expert systems, programming languages based on equational logic, algebraic specifications (e.g. OBJ), functional programming (e.g. ML) and transition systems (e.g. Murphi).Rule-based programming is currently experiencing a renewed period of growth with the emergence of new concepts and systems that allow one to better understand and better use it. From the theoretical side, after the in-depth study of rewriting concepts during the eighties, the nineties saw the emergence of the general concepts of rewriting logic and of the rewriting calculus. On the practical side, new languages, like ASM, ASF+SDF, Claire, ELAN and Maude, systems like LRR, and also commercial products, like Ilog Rules, have shown that the concept of rule could be of major interest as a programming tool. In particular, because it is now of practical use, fundamental questions arise, like the theoretical study of the algorithmic complexity of programs written in such languages, as well as their optimisation. Of course, semantics of such languages, compilation techniques and methodological studies of their use should also be explored.Rule based programming is closely related to both functional programming (when the term rewrite system is confluent and terminating) as well as classical logic programming (when the rewrite system is used for nondeterministic search).Accordingly, the purpose of this workshop is to bring together researchers from these various domains to foster fertilisation between theory and practice, as well as to favour the growth of this programming paradigm. Mark van den Brand(CWI Amsterdam)Iliano Cervesato(ITT Industries)Nachum Dershowitz(Tel-Aviv University)Bernd Fischer(RIACS/NASA Ames, Moffett Field)Claude Kirchner(LORIA Nancy)Jean-Yves Marion(LORIA Nancy)Narciso Marti-Oliet(Universidad Complutense de Madrid)Rakesh M. Verma(University of Houston)Eelco Visser(Utrecht University)This volume will be published as volume 44-2 in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URLWe would like to thank the program committee members for their help in evaluating the papers and making a scientifically interesting selection. Furthermore, we would like to thank the {\\bf PLI} organizing committee for taking care of the local organization of our workshop. We thank the ACM organization for sponsoring this workshop. We thank Elsevier for publishing these proceedings in the Electronic Notes in Theoretical Computer Science (ENTCS). Finally, we thank Professor Michael Mislove for providing and adapting the style files for ENTCS.November, 2001 Mark van den Brand and Rakesh M. Verma

Preface: Volume 55, Issue 2

RV'2001 Runtime VerificationThis volume contains the Proceedings of the First Workshop on Runtime Verification (RV'2001). The Workshop was held in Paris, France on 23 July 2001, as a satellite event to CAV'2001.The objective of RV'2001 was to bring scientists from both academia and industry together to debate on how to monitor, analyze and guide the execution of programs. The ultimate longer term goal is to investigate whether the use of lightweight formal methods applied during the execution of programs is a viable complement to the current heavyweight methods proving programs correct always before their execution, such as model checking and theorem proving. Dynamic program monitoring and analysis can occur during testing or during operation. The subject covers several technical fields as outlined below. •Dynamic Program Analysis. Techniques that gather information during program execution and use it to conclude properties about the program, either during test or in operation. Algorithms for detecting multi-threading errors in execution traces, such as deadlocks and data races.•Specification Languages and Logics. Formal methods scientists have investigated logics and developed technologies that are suitable for model checking and theorem proving, but monitoring can reveal new observation-based foundational logics.•Program Instrumentation. Techniques for instrumenting programs, at the source code or object code/byte code level, to emit relevant events to an observer.•Program Guidance. Techniques for guiding the behavior of a program once its specification is violated. This ranges from standard exceptions to advanced planning. Guidance can also be used during testing to expose errors.Both foundational and practical aspects of dynamic monitoring were encouraged.The papers in this volume were reviewed by the program committee consisting, besides editors, of Saddek Bensalem(VERIMAG Laboratory)Rance Cleaveland(State University of New York at Stony Brook)Michael Ernst(Massachusetts Institute of Technology)Patrice Godefroid(Bell Laboratories)Gerard Holzmann(Bell Laboratories)Jim Larus(Microsoft Research)Insup Lee(University of Pennsylvania)John Rushby(SRI International)Joseph Sifakis(VERIMAG Laboratory)Reid Simmons(Carnegie Mellon University)Olog Sokolsky(University of Pennsylvania)also by Susanne Graf, Moonjoo Kim, Oded Maler, Laurent Mounier, and Stavros Tripakis.This volume will be published as volume 55, issue 2, in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URL http://www.elsevier.nl/locate/entcsA printed version of the current volume is distributed to the participants at the workshop in Berlin.23 July 2001Klaus Havelund, Grigore Rosu

Preface: Volume 54

This volume contains the Proceedings of the International Workshop on Concurrency and Coordination, ConCoord. The Workshop was held in Lipari, Italy, on July 6-8, 2001, as a workshop associated to the 13th Lipari School for Computer Science Researchers. The Lipari School is a well established initiative attended every year by PhD students and researchers from Italy, Europe and the US. In 2001 the school was dedicated to the Foundations of Wide Area Network Programming.The goal of the workshop was to study the concurrency and coordination aspects of global computing, which has recently become more and more promising due to widespread web applications. The emerging programming paradigms require formal models, programming primitives and effective infrastructures to handle mobility of code and computations, control of dynamically loaded software modules, and more generally coordination and orchestration of distributed applications. Similar aims have been pursued by two ESPRIT working groups, which recently terminated their activity: CONFER-2 (CONcurrency and Functions: Evaluation and Reduction) led by Jean-Jacques Levy and COORDINA (from COORDINAtion models to applications), led by Antonio Porto.The Program Committee consisted of Farhad Arbab (CWI, Amsterdam); Jean-Jacques Levy (Inria Roquencourt); Ugo Montanari (University of Pisa, co-chair); Antonio Porto (Universidade Nova De Lisboa); Vladimiro Sassone (University of Sussex and University of Catania, co-chair) and Björn Victor (Uppsala University). The Organizing Committee of ConCoord consisted of Alfredo Ferro (University of Catania), Ugo Montanari and Vladimiro Sassone.The papers in this volume were reviewed by the program committee members and by Chiara Bodei, Roberto Bruni, Michele Bugliesi, Luis Caires, Alessandro Fantechi, Kohei Honda, Francesca Levi, Massimo Merro, Giuseppe Milicia, Ana Moreira, Uwe Nestmann, Rosario Pugliese, Davide Sangiorgi, Francesca Scozzari, Alan Schmitt and Laura Semini.This volume will appear in the series Electronic Notes in Theoretical Computer Science (ENTCS), a series published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URL http://www.elsevier.nl/locate/entcsJuly 2001Ugo Montanari and Vladimiro Sassone

Preface: Volume 50, Issue 4

IntroductionVerification of Parameterized Systems - VEPAS 2001This part of the volume contains the Proceedings of the ICALP 2001 Satellite Workshop on Verification of Parameterized Systems (VEPAS 2001), held in the Aldemar Knossos Royal Village Hotel, Hersonissos, Crete, Greece on 13 July 2001.Previously, abstract models used in formal verification could be classified into finite-state models and infinite-state models. This distinction begins to blur as a new field emerges: “parameterized verification”. In parameterized verification the abstract models can contain parameters. Thus, they do not represent single instances of systems, but actually whole (possibly infinite) classes of instances. The goal is to show the correctness independently of the parameter and thus for the whole class. For example, one wants to show the correctness of a communication protocol for an arbitrary number n of participants or the correctness of an elevator control software for an arbitrary number n of floors. Parameterized verification is of special importance w.r.t. scalability of systems, i.e., one wants to show the correctness of a system with a certain basic structure independently of its size. While proof techniques have been used for such problems for some time, more recently also algorithmic and semi-algorithmic approaches are being developed. These often use automata theoretic models and acceleration techniques.The main topics of VEPAS 2001 were the following: •Abstract models for systems with an arbitrary number of components.•Scalability of systems and verification methods.•Abstraction methods and proof techniques in verification.•Automata theoretic models, fixpoints and acceleration methods.•Combinations of algorithms and proof techniques.VEPAS 2001 was one of the four satellite workshops of the 28th International Colloquium on Automata, Languages and Programming (ICALP 2001), held in Crete, Greece, July 8-12, 2001.The five papers in this volume were selected by the Program Committee from nine submissions received in response to a Call for Papers. The proceedings appear as Volume 50 No. 4 in the series Electronic Notes in Theoretical Computer Science (ENTCS). The volumes in the ENTCS series can be accessed at the URL http://www.elsevier.nl/locate/entcs.The program committee of VEPAS 2001 consisted of the following people: •Ahmed Bouajjani (Université Paris 7, France)•Bengt Jonsson (Uppsala University, Sweden)•Antonín Kucera (Masaryk University, Czech Republic)•Richard Mayr (chair) (Albert-Ludwigs University Freiburg, Germany)•A. Prasad Sistla (University of Illinois at Chicago, USA)We would like to thank Christos Zaroliagis (ICALP 2001 Satellite Workshops Coordinator) for his continuous support. Many thanks are due to Parosh Abdulla and Ahmed Bouajjani (Invited Speakers) and to the members of the Program Committee as well as their sub-referees for their accurate work.July 2001 Richard Mayr

Preface: Volume 50, Issue 2

IntroductionBohm's theorem: applications to Computer Science Theory - BOTH 2001This part of the volume contains the Proceedings of the ICALP 2001 Satellite Workshop on Bohm's theorem: applications to Computer Science Theory (BOTH 2001), held in the Aldemar Knossos Royal Village Hotel, Hersonissos, Crete, Greece on 13 July 2001.Bohm's theorem is central to the study of the untyped lambda calculus. It shows that disctinct normal forms, up to eta conversion, cannot be identified in any consistent model of the lambda calculus. This first separability result has been generalised to non normal forms and is the underlying concept for the introduction of finite or infinite trees of head normal forms, also known as Bohm trees.In the semantics of programming languages, Bohm's theorem corresponds to the notion of full abstraction in models, and gave the initial hints towards the construction of models for sequential languages; in the theory of concurrency, it is the notion of observability and is used for building bisimulations; in the semantics of security, it gives a strong meaning to the notion of safe computations.Thirty years later, on the occasion of Corrado Bohm's EATCS Distinguished Service Award, this workshop attempted to provide a synthetic view as well as the most recent results on Bohm trees, sequentiality and game semantics, logic, security, fully abstract translations, action calculi, abstract rewriting systems, based on the seminal work of Bohm.BOTH 2001 was one of the four satellite workshops of the 28th International Colloquium on Automata, Languages and Programming (ICALP 2001), held in Crete, Greece, July 8-12, 2001.The proceedings appear as Volume 50 No. 2 in the series Electronic Notes in Theoretical Computer Science (ENTCS). The volumes in the ENTCS series can be accessed at the URL http://www.elsevier.nl/locate/entcs.The Program Committee selected five contributions by researchers from several different countries: France, Italy, Japan, Yugoslavia. Selected contributions are connected to Bohm's theorem or Bohm's research. The program included also two invited talks by Henk Barendregt (Univ. of Nijmegen) and Mariangiola Dezani (Univ. di Torino). Pierre-Louis Curien also offered to give a talk on Separation in Girard's Ludical framework.The program committee of BOTH 2001 consisted of the following people: •Pierre-Louis Curien (CNRS, Univ. of Paris 7)•Gérard Huet (INRIA, France)•Jan-Willem Klop (Free University, Amsterdam)•Jean-Jacques Lévy (INRIA, France)•Harry Mairson (Boston University)•Gordon Plotkin (Univ. of Edinburgh)•Simona Ronchi (Univ. of Torino)We would like to thank Christos Zaroliagis (ICALP 2001 Satellite Workshops Coordinator) for his continuous support.July 2001 Jean-Jacques Lévy

Preface: Volume 44, Issue 4

This volume contains the contributions of the workshop Uniform Approaches to Graphical Process Specification Techniques (UNIGRA'01) held in Genova (31.3. – 1.4.2001) as a satellite of ETAPS 2001. The main idea of this workshop has been to bring together various unifying approaches from the areas of graph transformations, visual modeling techniques and Petri nets due to the increasing amount of divergent formalisms in each of these areas.According to this main idea, this volume presents uniform approaches and further introduces unifying and comparative studies between these fields and related areas.The first part contains contributions from the area of graph transformation with new aspects of GRACE by Kreowski et al. and high-level replacement systems by Parisi-Presicce as unifying approaches to graph transformations and related specification techniques. The main ideas concerning the common exchange formats for graphs and graph transformations discussed within the APPLIGRAPH project and a dynamic meta model for graph transformation approaches are presented in the papers by Taentzer and Heckel, Zündorf respectively. Related work can be found in the handbooks of graph grammars and computing by graph transformation as well as in the proceedings of GRATRA 2000, a satellite of ETAPS 2000.In the second part concerning visual modeling techniques, new aspects of the visual language environments GenGEd and DIAGEN are discussed by Ermel et.al. as well as Minas and Hoffmann respectively. Formal concepts improving different aspects of the UML are studied in three contributions by Groβe-Rhode, Schürr as well as Baresi and Pezze respectively. Related work has been presented at GT-VMT'00, a satellite of ICALP'00 in Geneve and will be presented at GT-VMT'01 as a satellite of ICALP'01 at Heraklion.In the third part, three unifying approaches for Petri nets are proposed by Dehnert et al., Meseguer et al. and by Juhás et al. The first contribution presents the second installment of the “Petri Net Baukasten” developed within the DFG research group “Petri Net Technology”. The first installment has been introduced already at the PNT-Colloquium 1999 in Berlin. A unified presentation of low- and high-level Petri nets is given by Meseguer using their famous unifying framework of rewriting logic. A unified approach for different types of firing rules of Petri nets is given in the paper of Juhás et al. based on partial algebras. A more detailed collection of unifying approaches to Petri Nets is going to appear in a new volume of the series Advances in Petri Net, edited by Ehrig, Juhás, Padberg and Rozenberg.The workshop has stimulated lively discussions between the 35 participants and will certainly lead to further fruitful cooperations.The following program committee of UNIGRA'01 has given valuable scientific support before and during the workshop:Roswitha Bardohl (TU Berlin)Hartmut Ehrig (TU Berlin) [co-chair]Gregor Engels (University of Paderborn)Gabriel Juhas (University of Bratislava/KU Eichstätt)Hans-Järg Kreowski (University of Bremen)Ugo Montanari (University of Pisa)Fernando Orejas (University of Catalunya, Barcelona)Julia Padberg (TU Berlin) [co-chair]Francesco Parisi-Presicce (University La Sapienza, Rome)Grzegorz Rozenberg (University of Leiden)The next UNIGRA workshop is planned as satellite of ETAPS 2003 in Warsaw.This volume will be published as volume 44.4 in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URL http://www.elsevier.nl/locate/entcsThe editors of this volume are most grateful to the organizers of ETAPS'01 and the publisher of ENTCS for their valuable support.Berlin and Genova, May 2001 Hartmut EhrigClaudia ErmelJulia Padberg

Preface: Volume 44, Issue 2

ForewordThis volume contains the Proceedings of the First Workshop on Language Descriptions, Tools and Applications (LDTA'01). The Workshop was held in Genova, Italy on April 7, 2001, as satellite event to ETAPS'2001.This is the first edition of the Workshop on Language Descriptions, Tools and Applications. It is a combination of the “Workshop on Attribute Grammars and their Applications” and the former ASF+SDF workshops. Both workshop series had as theme the description of (programming) languages and the development and/or generation of tools for these languages based on formal descriptions. With this new workshop we hope to achieve a cross-fertilization of research in this area by bringing together researchers from various schools (attribute grammars, algebraic approaches, action semantics, operational semantics, and denotational semantics) working on language descriptions. The workshop also aims at bringing together people from the theoretical side as well as people who develop tools and work on applications.The LDTA'2001 program consists of 9 papers, which were selected from 18 submissions, one invited talk by Paul Klint on “Collaborative Development of Interactive Language Processing Tools”, and 4 tool demonstrations. The selected papers cover a broad range of themes like: object oriented tree traversal and attribute grammars, action semantics, rewriting engines, document transformation, and the use of XML and JAVA in combination with attribute grammars. The tool demonstrations include presentations of the ASF+SDF Meta-Environment, SmartTools, Stratego, and an action semantics environment.The papers in this volume were reviewed by the program committee consisting of Isabelle Attali(INRIA Sophia Antipolis)Mark van den Brand(CWI Amsterdam)Görel Hedin(Lund University)Jan Heering(CWI Amsterdam)Pierre-Etienne Moreau(LORIA Nancy)Marjan Mernik(University of Maribor)Peter D. Mosses(BRICS Aarhus)Didier Parigot(INRIA Sophia Antipolis)Günter Riedewald(University of Rostock)Eelco Visser(Utrecht University)David Watt(University of Glasgow)This volume will be published as volume 44-2 in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URL http://www.elsevier.nl/locate/entcsWe would like to thank the program committee members for their help in evaluating the papers and making a scientifically interesting selection. Furthermore, we would like to thank the ETAPS organizing committee for taking care of the local organization of our workshop. We thank Elsevier for publishing these proceedings in the Electronic Notes in Theoretical Computer Science (ENTCS). Finally, we thank Professor Michael Mislove for providing and adapting the style files for ENTCS.Mark van den Brand and Didier ParigotJune, 2001

Preface: Volume 39

A large class of systems can be specified and verified by abstracting away from the temporal aspects. This is the class of systems where time affects the performance but not the functional behaviour. In time-critical systems, instead, time issues become essential. Their correctness depends not only on which actions a system can perform but also on their execution time. Due to their importance, time-critical systems have attracted the attention of a considerable number of computer scientists from various research areas.This volume contains the Proceedings of the International Workshop on Models for Time-Critical Systems (MTCS 2000), held in State College (Pennsylvania, USA) 26 August 2000. The objectives of the workshop were (i) to validate the more promising proposals on models for time-critical systems and (ii) to promote interaction between different research areas in the field of time-critical systems.MTCS 2000 was one of the four satellite workshops of the 11th International Conference on Concurrency Theory (CONCUR 2000), held in State College (Pennsylvania, USA) 22-25 August 2000. The other three were: 7th International Workshop on Expressiveness in Concurrency (EXPRESS'00), 2nd Workshop on Geometric and Topological Methods in Concurrency Theory (GETCO 2000) and Why Object-Orientation (Y00).The six papers in this volume were selected by the Program Committee from submissions received in response to a Call for Papers. The final proceedings will appear as Volume 39 in the series Electronic Notes in Theoretical Computer Science (ENTCS). The volumes in the ENTCS series can be accessed at the URLhttp://www.elsevier.nl/locate/entcsWe would like to thank Catuscia Palamidessi and Dale Miller (CONCUR 2000 Conference Chairs) and Uwe Nestmann (Satellite Workshops Chair) for the opportunity they gave us to organize MTCS 2000 and for their continuous support. Many thanks are due to Thomas Henzinger (Invited Speaker) and to the members of the Program Committee as well as their sub-referees for their accurate work. We would also like to thank Michael Mislove for his help during the proceedings editorial process.Rajeev Alur(USA)Frank de Boer(NL)Flavio Corradini(IT)Roberto Gorrieri(IT)Paola Inverardi(IT)Amir Pnueli(IL)Bran Selic(CA)Joseph Sifakis(FR)Walter Vogler(DE)

Preface: Volume 30, Issue 3

One of the main areas of research in logic programming is the design and implementation of sequential and parallel (constraint) logic programming systems. This research goes broadly from the design and specification of novel implementation technology to its actual evaluation in real life situations. A series of workshops on Implementations of Logic Programming Systems, previously held in Budapest (1993), Ithaca (1994), Portland (1995), Bonn (1996), Port Jefferson (1997), Manchester (1998) and Las Cruces (1999) provided a forum for ongoing research on the design and implementation of sequential and parallel (constraint) logic programming systems.This volume contains a collection of papers presented at the Workshop on Parallelism and Implementation Technology for (Constraint) Logic Programming, held in Las Cruces on December 1st, 1999, in conjunction with ICLP'99. The workshop was sponsored and organised by COMPULOG AMERICAS. The workshop also received support from the Association for Logic Programming and from the Department of Computer Science, New Mexico State University.Papers from both academia and industry were invited. Preference was given to the analysis and description of implemented systems (or currently under implementation) and their associated techniques, problems found in their development or design, and steps taken towards the solution of these problems.Topics included, but were not limited to: •standard and non—standard sequential implementation schemes (e.g., generalization/modification of WAM, translation to C, etc.);implementation of parallel logic programming systems;balance between compile-time effort and run-time machinery;techniques for the implementation of different declarative programming paradigms based on, or extending, logic programming (e.g., constraint logic programming, concurrent constraint languages, equational-logic languages);performance evaluation of sequential and parallel logic programming systems, both through benchmarking and using real world applications;other implementation-related issues, such as memory management, register allocation, use of global optimisations, etc.We were very fortunate to have so many interesting research papers, ranging over widely different subjects and giving a broad coverage of current research in sequential and parallel implementation of logic programming systems. Papers on sequential logic programming systems, focus on varied topics: constraint evaluation, support for extensions to logic programming, and abstract machines for performance evaluation. Papers on parallel logic programming systems also focus on diverse topics ranging from distributed implementations, garbage collection, to optimisations for exploiting and-or parallelism.The editors would like to thank all authors that chose to submit their work to this book, and also for their cooperation in making this document possible. We would also like to thank all referees involved in assessing the papers in this special volume.This volume will be published as volume 30, Issue 3 in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URL http://www.elsevier.nl/locate/entcsMarch 14, 2000Horst Reichel