The main idea behind the series of volumes Advances in Petri Nets is to present to the general computer science community recent results which are the most representative and significant for the development of the area. Thepapers for the volumes are drawn mainly from the annual International Conferences on Applications and Theory of Petri Nets. Selected papers from the latest conference are independently refereed, and revised and extended as necessary. Some further papers submitted directly to the editor are included. Advances in Petri Nets 1991 covers the 11th International Conference on Applications and Theory of Petri Nets held in Paris, France in June 1991. The volume contains the Bibliography of Petri Nets 1990 prepared by H. Pl}nnecke and W. Reisig, with over 4000 entries.

The third European Software Engineering Conference follows ESEC'87 and ESEC'89. This series of conferences was set up by the European societies with the aim of providing an international forum for researchers, developersand users of software engineering technology. The need for a meeting point to discuss new results and useful experiences was clear from the large amount of high-quality European software engineering researchin recent years, stimulated, for example, through major European research programmes. The 22 papers in these proceedings were selected from 133 papers submitted from 26 different countries. They cover a fairly broad range of themes such as formal methods and practical experiences with them, special techniques for real-time systems, software evolution and re-engineering, software engineering environments, and software metrics. Invited papers by well-known experts address further important areas: perspectives on configuration management, software factories, user interfacedesign, computer security, and technology transfer.

CONCUR'91 is the second international conference on concurrency theory, organized in association with the NFI project Transfer. It is a sequel to the CONCUR'90 conference. Its basic aim is to communicate ongoing work in concurrency theory. This proceedings volume contains 30 papers selected for presentation at the conference (from 71 submitted) together with four invited papers and abstracts of the other invited papers. The papers are organized into sections on process algebras, logics and model checking, applications and specification languages, models and net theory, design and real-time, tools and probabilities, and programming languages. The proceedings of CONCUR'90 are available asVolume 458 of Lecture Notes in Computer Science.

This book presents a coherent description of the theoretical and practical aspects of Coloured Petri Nets (CP-nets or CPN). It shows how CP-nets have been de veloped - from being a promising theoretical model to being a full-fledged lan guage for the design, specification, simulation, validation and implementation of large software systems (and other systems in which human beings and/or com puters communicate by means of some more or less formal rules). The book contains the formal definition of CP-nets and the mathematical theory behind their analysis methods. However, it has been the intention to write the book in such a way that it also becomes attractive to readers who are more interested in applications than the underlying mathematics. This means that a large part of the book is written in a style which is closer to an engineering textbook (or a users' manual) than it is to a typical textbook in theoretical computer science. The book consists of three separate volumes. The first volume defines the net model (i. e. , hierarchical CP-nets) and the basic concepts (e. g. , the different behavioural properties such as deadlocks, fair ness and home markings). It gives a detailed presentation of many small exam ples and a brief overview of some industrial applications. It introduces the for mal analysis methods. Finally, it contains a description of a set of CPN tools which support the practical use of CP-nets.

A Petri net is a mathematical representation of a network. This book first introduces the basic models including time and stochastic extensions, in particular place-transition and high level Petri nets. Their modeling and design capabilities are illustrated by a set of representations of interest in operating and communication systems. The volume then addresses the related verification problems and proposes corresponding solutions by introducing the main notions needed to fully understand the behavior and properties behind Petri nets. Particular attention is devoted to how systems can be fully represented and analyzed in terms of their behavioral, time, and stochastic aspects by using the same formal approach and semantic basis. Finally, illustrative examples are presented in the important fields of interoperability in telecommunication services, programming languages, multimedia architectures, manufacturing systems, and communication protocols.

This book constitutes the refereed proceedings of the 20th International Conference on Application and Theory of Petri Nets, ICATPN'99, held in Williamsburg, Virginia, USA, in June 1999. The 21 revised full papers presented were carefully selected from 45 submissions. Also included are three invited presentations. The book presents state-of-the-art research results on all current aspects of Petri nets as well as advanced applications in a variety of areas.

The REX School/Symposium "A Decade of Concurrency - Reflections and Perspectives" was the final event of a ten-year period of cooperation between three Dutch research groups working on the foundations of concurrency. Ever since its inception in 1983, the goal of the project has been to contribute to the cross-fertilization between formal methods from the fields of syntax, semantics, and proof theory, aimed at an improved understanding of the nature of parallel computing. The material presented in this volume was prepared by the lecturers (and their coauthors) after the meeting took place. In total, the volume constitutes a thorough state-of-the-art report of the research activities in concurrency.

This book presents a new concurrent logic programming language called Conclog and a methodology for programming in it. Conclog was designed bytaking the ideal features of logic programming as reference, rather than by concentrating directly on operational tricks to ensure efficiency. This leads to quite easy declarative programming. Concern for soundness and completeness ensures that multi-directional and multi-solution correct procedures can be coded quite straightforwardly. Assuming suitable hypotheses on their uses, they can be transformed into very efficient versions thanks to the introduction of appropriate control information. Correctness-preserving properties are given for that purpose. The designof Conclog involves three steps. First, a sound and complete parallel execution model of Horn clause programs is proposed which reduces subgoals of conjunctions independently and uses a calculus for reconciling inconsistent bindings. Second, this is extended to handle negation as completely as possible. Third, a minimal and reasonably complete set of extra-logical features are defined for optimization and practical purposes. The second part of the book presents a methodology for constructing Conclog in a rigorous way. This covers the entire programming process, from informal specifications via logic descriptions to efficient programs. The methodology can be adapted to other languages.

The proceedings of the fourth Vienna Development Method Symposium, VDM'91, are published here in two volumes. Previous VDM symposia were held in 1987 (LNCS 252), 1988 (LNCS 328), and 1990 (LNCS 428). The VDM symposia have been organized by VDM Europe, formed in 1985 as an advisory board sponsored by the Commission of the European Communities. The VDM Europe working group consisted of researchers, software engineers, and programmers, allinterested in promoting the industrial usage of formal methods for software development. The fourth VDM symposium presented not only VDM but also a large number of other methods for formal software development. Volume 1 contains conference contributions. It has four parts: contributions of invited speakers, papers, project reports, and tools demonstration abstracts. The emphasis is on methods and calculi for development, verification and verification tools support, experiences from doing developments, and the associated theoretical problems. Volume 2 contains four introductory tutorials (on LARCH, Refinement Calculus, VDM, and RAISE) and four advanced tutorials (on ABEL, PROSPECTRA, The B Method, and The Stack). They present a comprehensive account of the state of theart.