Semantics for Concurrency

The semantics of concurrent systems is one of the most vigorous areas of research in theoretical computer science, but suffers from disagree ment due to different, and often incompatible, attitudes towards abstracting non-sequential behaviour. When confronted with process algebras, which give rise to very elegant, highly abstract and com positional models, traditionally based on the interleaving abstraction, some argue that the wealth of contribution they have made is partially offset by the difficulty in dealing with topics such as faimess. On the other hand, the non-interleaving approaches, based on causality, although easing problems with fairness and confusion, still lack struc ture, compositionality, and the elegance of the interleaving counter parts. Since both these approaches have undoubtedly provided important contributions towards understanding of concurrent systems, one should concentrate on what they have in common, rather than the way they differ. The Intemational Workshop on Semantics for Concurrency held at the University of Leicester on 23-25 July 1990 was organised to help overcome this problem. Its main objective was not to be divisive, but rather to encourage discussions leading towards the identification of the positive objective features of the main approaches, in the hope of furthering common understanding. The Workshop met with an excel lent response, and attracted contributions from all over the world. The result was an interesting and varied programme, which was a combi nation of invited and refereed papers. The invited speakers were: Prof. dr. E. Best (Hildesheim University) Prof. dr. A.

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This volume contains a collection of papers presented at the International Workshop on Semantics for Concurrency, held from 22 to 25 July 1990 at the University of Leicester, UK. The main aim of the workshop was to discuss and seek to identify the positive objective features of the main approaches to semantics for concurrency, and thus to increase understanding between research groups. The field of semantics for concurrency has attracted a number of formalisms, ranging from algebra and automata theory, through logic and topology to category theory. This pluralism provides valuable insight into the nature of concurrency, but when coupled with different views of what issues are important when modeling concurrency, it leads also to disjointed research efforts and lack of communication. Discussions then concentrate on superficial, rather than objective, differences between approaches, and it becomes harder to assess which features of a particular approach are successful in dealing with the problems of concurrent behaviors. This workshop was organized to coordinate research and increase communication. These proceedings include papers on a wide range of issues in concurrency, including: process algebras and equivalences, Petri nets, dataflow networks, logics for concurrency, and denotational, partial-order and real-time semantics.

Contenu
A General Tableau Technique for Verifying Temporal Properties of Concurrent Programs (Extended Abstract).- Traps, Free Choice and Home States (Extended Abstract).- A Denotational Semantics for Synchronous and Asynchronous Behavior with Multiform Time (Extended Abstract).- From Failure to Success: Comparing a Denotational and a Declarative Semantics for Horn Clause Logic.- Negations of Transactions and Their Use in the Specification of Dynamic and Deontic Integrity Constraints.- Experimenting with Process Equivalence.- Iteration Theories of Synchronization Trees.- Towards a Theory of Parallel Algorithms on Concrete Data Structures.- Causal Automata I: Confluence ? (AND, OR) Causality.- A Simple Generalization of Kahn's Principle to Indeterminate Dataflow Networks (Extended Abstract).- Defining Fair Merge as a Colimit: Towards a Fixed-Point Theory for Indeterminate Dataflow.- High-Level Nets for Dynamic Dining Philosophers Systems.- Formalizing the Behaviour of Parallel Object-Based Systems by Petri Nets.- High Level Distributed Transition Systems.- A Compositional Axiomatisation of Safety and Liveness Properties for Statecharts.- Defining Conditional Independence Using Collapses.- Timed Concurrent Processes.- Approaching a Real-Timed Concurrency Theory.- On Global-Time and Inter-Process Communication.- Modelling Reactive Hardware Processes Using Partial Orders.- Author Index.