A general basis for the definition of a finite but unbounded number of parallel processes is the equation S(n; dt) = P (0; get(0; dt))/ eq(n; 0) .(P (n; get(n; dt)) k S(n \Gamma 1; dt)). In this formula eq(n; 0) is an equality test, and get(n; dt) denotes the n-th data element in table dt . We derive a linear process equation with the same behaviour as S(n; dt ), and show that this equation is well-defined, provided one adopts the principle CL-RSP from [4]. In order to demonstrate the strength of our result, we use it for the analysis of a standard example. We show that n + 1 concatenated buffers form a queue of capacity n + 1. 1 Introduction Distributed algorithms are often configured as an arbitrarily large but finite set of processors that run a similar program. Using the formalism CRL (micro Common Representation Language [9]) this can be described, using recursion and operators for parallelism. Several benchmark verifications in CRL and process algebra are therefore based on the...

We report on our experience in using the Isabelle/HOL theorem prover to mechanize proofs of observation equivalence for systems with infinitely many states, and for parameterized systems. We follow the direct approach: An infinite relation containing the pair of systems to be shown equivalent is defined, and then proved to be a weak bisimulation. The weak bisimilarity proof is split into many cases, corresponding to the derivatives of the pairs in the relation. Isabelle/HOL automatically proves simple cases, and guarantees that no case is forgotten. The strengths and weaknesses of the approach are discussed.

In [10] Groote and Springintveld incorporated several model-oriented techniques { such asinvariants, matching criteria, state mappings { in the process-algebraic framework of CRL for structuring and simplifying protocol veri cations. In this paper, we formalise these extensions in Coq, which is a proof development tool based on type theory. In the updated framework, the length of proof constructions is reduced significantly. Moreover, the new approach allows for more automation (proof generation) than was possible in the past. The results are illustrated by an example in which we prove two queue representations equal. 1

We show that defining a finite but unbounded number of parallel processes using the equation S(k, dt) = P (0, get(0, dt))/eq(k, 0).(S(k - 1, dt) || P (k, get(k, dt))) is well defined, if one adopts the principle CL-RSP. We also provide means to easily derive a linear process equation with the same behaviour as S(k, dt).

Network algebra is proposed as a uniform algebraic framework for the description and analysis of dataflow networks. An equational theory of networks, called BNA (Basic Network Algebra), is presented. BNA, which is essentially a part of the algebra of flownomials, captures the basic algebraic properties of networks. For asynchronous dataflow networks, additional constants and axioms are given; and a corresponding process algebra model is introduced. This process algebra model is compared with previous models for asynchronous dataflow. Keywords & Phrases: dataflow networks, network algebra, process algebra, asynchronous dataflow, feedback, merge anomaly, history models, oracle based models, trace models. 1994 CR Categories: F.1.1, F.1.2, F.3.2., D.1.3., D.3.1. This paper is an abridged version of [1]. The full version covers synchronous dataflow networks as well. y Partially supported by ESPRIT BRA 8533 (NADA) and ESPRIT BRA 6454 (CONFER). x On leave (1996--1997) at Unit...

We specify the tree identify protocol of a high performance serial multimedia bus (IEEE standard 1394 [IEE95]) in three different levels of detail using ¯CRL [GP95]. We propose using the cones and foci verification technique of Groote and Springintveld [GS95] to show the descriptions equivalent under branching bisimulation. The proof of the equivalence of the two more abstract specifications is shown in detail and the proof of the equivalence of the most abstract and the more complex description, which is work in progress, is sketched. 1 Introduction Much time and effort is expended in the development of new techniques for description and analysis of (computer) systems; however, many of these techniques remain the preserve only of their inventors, and are never widely used. This is often due to the sharp learning curve required to adopt them; many verification techniques have complex theoretical underpinnings, and require sophisticated mathematical skills to apply them. The study pre...

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