Reo is an exogenous coordination language for compositional construction of component connectors based on a calculus of channels. Building automated tools to address such concerns as equivalence or containment of the behavior of two given connectors, verification of the behavior of a connector, etc. requires an operational semantic model suitable for model checking. In this paper we introduce constraint automata and propose them as a semantic model for Reo.

Abstract. Van Glabbeek (1990) presented the linear time/branching time spectrum of behavioral equivalences for finitely branching, concrete, sequential processes. He studied these semantics in the setting of the basic process algebra BCCSP, and tried to give finite complete axiomatizations for them. Obtaining such axiomatizations in concurrency theory often turns out to be difficult, even in the setting of simple languages like BCCSP. This has raised a host of open questions that have been the subject of intensive research in recent years. Most of these questions have been settled over BCCSP, either positively by giving a finite complete axiomatization, or negatively by proving that such an axiomatization does not exist. Still some open questions remain. This paper reports on these results, and on the state-of-the-art in axiomatizations for richer process algebras with constructs like sequential and parallel composition. 1

This paper gives an equational axiomatization of probabilistic bisimulation equivalence for a class of finite-state agents previously studied by Stark and Smolka ((2000) Proof, Language, and Interaction: Essays in Honour of Robin Milner, pp. 571-595). The axiomatization is obtained by extending the general axioms of iteration theories (or iteration algebras), which characterize the equational properties of the fixed point operator on (#-)continuous or monotonic functions, with three axiom schemas that express laws that are specific to probabilistic bisimilarity.

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Specifications of system behaviour tend to become large. Analysis of such specifications requires automated tools. Most attention hitherto has been invested in fully automatic tools. We however believe that in many cases human intervention is required and we therefore propose a number of computer tools to transform process specifications. The concrete manipulation tools that we describe can eliminate constants, redundant sum variables and parameters, and allow to split variables ranging over complex datatypes. These tools can transform specifications with large finite state spaces to variants with state spaces being a fraction of their original size, and transform specifications with infinite state spaces to those with finite state spaces. 2000 Mathematics Subject Classification: 68M14, 68Q60, 68Q85 Keywords and Phrases: Automated Reasoning, Distributed systems, Linear Process Equations, Model Checking, Verification Note: Research carried out in SEN2, with financial support of the "Systems Validation Center". 1.

We introduce the lambda-coiteration schema for a distributive law lambda of a functor T over a functor F. Under certain conditions it can be shown to uniquely characterise functions into the carrier of a final F-coalgebra, generalising the basic coiteration schema as given by finality. The duals of primitive recursion and course-of-value iteration, which are known extensions of coiteration, arise as instances of our framework. One can furthermore obtain schemata justifying recursive specifications that involve operators such as addition of power series, regular operators on languages, or parallel and sequential composition of processes. Next...

We have designed a tool to simplify model checking of Erlang programs by translating Erlang into a process algebra with data, called µCRL. As a case-study for this tool we focused on a simplied locker implementation after the locker that is present in the control software of the AXD 301 switch. The translation algorithm has been developed to handle this production-like code. We use the tools accompanying CRL to generate the transition systems from the specification generated by our tool. With the Caesar/Aldebaran tool set, we verified properties for our case-study.

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The process-algebraic language mcrl is used to analyze an existing distributed system for lifting trucks. Four errors were found in the original design. We propose solutions for these problems and show by means of model-checking that the modified system meets the requirements.