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114
Barbed Bisimulation
, 1992
"... Machine [8]. In this technique, axioms for a structural congruence relation are introduced prior to the reduction system, in order to to break a rigid, geometrical vision of concurrency; then reduction rules can easily be presented in which redexes are indeed subterms again. It can then be shown 1 ..."
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Cited by 233 (20 self)
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Machine [8]. In this technique, axioms for a structural congruence relation are introduced prior to the reduction system, in order to to break a rigid, geometrical vision of concurrency; then reduction rules can easily be presented in which redexes are indeed subterms again. It can then be shown 1 that modulo structural congruence the reduction relation exactly represents the silent action of the transition semantics. It is left as an open problem in [11] how to recover from such a formulation the familiar congruences which are based upon a labelled transition system. It turns out that this is not a trivial problem. We tackle it in this paper for the simple case of CCS and strong observational equivalence (). Because the reduction relation coincides with the silent action \Gamma! of the labelled transition system (as mentioned above), we can remain within the latter framework. But we wish to retain the spirit of the reduction semantics as far as possible, in the sense that we wish t...
The πcalculus as a theory in linear logic: Preliminary results
 3rd Workshop on Extensions to Logic Programming, LNCS 660
, 1993
"... The agent expressions of the πcalculus can be translated into a theory of linear logic in such a way that the reflective and transitive closure of πcalculus (unlabeled) reduction is identified with “entailedby”. Under this translation, parallel composition is mapped to the multiplicative disjunct ..."
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Cited by 102 (17 self)
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The agent expressions of the πcalculus can be translated into a theory of linear logic in such a way that the reflective and transitive closure of πcalculus (unlabeled) reduction is identified with “entailedby”. Under this translation, parallel composition is mapped to the multiplicative disjunct (“par”) and restriction is mapped to universal quantification. Prefixing, nondeterministic choice (+), replication (!), and the match guard are all represented using nonlogical constants, which are specified using a simple form of axiom, called here a process clause. These process clauses resemble Horn clauses except that they may have multiple conclusions; that is, their heads may be the par of atomic formulas. Such multiple conclusion clauses are used to axiomatize communications among agents. Given this translation, it is nature to ask to what extent proof theory can be used to understand the metatheory of the πcalculus. We present some preliminary results along this line for π0, the “propositional ” fragment of the πcalculus, which lacks restriction and value passing (π0 is a subset of CCS). Using ideas from prooftheory, we introduce coagents and show that they can specify some testing equivalences for π0. If negationasfailuretoprove is permitted as a coagent combinator, then testing equivalence based on coagents yields observational equivalence for π0. This latter result follows from observing that coagents directly represent formulas in the HennessyMilner modal logic. 1
Model Checking Mobile Processes
, 1993
"... We introduce a temporal logic for the polyadic ßcalculus based on fixed point extensions of HennessyMilner logic. Features are added to account for parametrisation, generation, and passing of names, including the use, following Milner, of dependent sum and product to account for (unlocalised) inpu ..."
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Cited by 68 (11 self)
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We introduce a temporal logic for the polyadic ßcalculus based on fixed point extensions of HennessyMilner logic. Features are added to account for parametrisation, generation, and passing of names, including the use, following Milner, of dependent sum and product to account for (unlocalised) input and output, and explicit parametrisation on names using lambdaabstraction and application. The latter provides a single name binding mechanism supporting all parametrisation needed. A proof system and decision procedure is developed based on Stirling and Walker's approach to model checking the modal ¯calculus using constants. One difficulty, for both conceptual and efficiencybased reasons, is to avoid the explicit use of the !rule for parametrised processes. A key idea, following Hennessy and Lin's approach to deciding bisimulation for certain types of valuepassing processes, is the relativisation of correctness assertions to conditions on names. Based on this idea a proof system and ...
Testing equivalence for mobile processes
 Proceedings of CONCUR ’92, LNCS 630
, 1995
"... Abst rac t. The impact of applying the testing approach to a calculus of processes with a dynamically changing structure is investigated. A proof system for the finite fragment of the calculus is introduced which consists of two groups of laws: those for strong observational equivalence and those ne ..."
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Cited by 66 (10 self)
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Abst rac t. The impact of applying the testing approach to a calculus of processes with a dynamically changing structure is investigated. A proof system for the finite fragment of the calculus is introduced which consists of two groups of laws: those for strong observational equivalence and those needed to deal with x actions. Soundness and completeness w.r.t, a testing preorder are shown. A fully abstract denotational model for the language is presented which relies on the existence of normal forms for processes. 1.
A Theory of Bisimulation for the picalculus
, 1993
"... We study a new formulation of bisimulation for the calculus [MPW92], which we have called open bisimulation ( ). In contrast with the previously known bisimilarity equivalences, is preserved by all calculus operators, including input prefix. The differences among all these equivalences alread ..."
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Cited by 53 (0 self)
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We study a new formulation of bisimulation for the calculus [MPW92], which we have called open bisimulation ( ). In contrast with the previously known bisimilarity equivalences, is preserved by all calculus operators, including input prefix. The differences among all these equivalences already appear in the sublanguage without name restrictions: Here the definition of can be factorised into a "standard" part which, modulo the different syntax of actions, is the CCS bisimulation, and a part specific to the calculus, which requires name instantiation. Attractive features of are: a simple axiomatisation (of the finite terms), with a completeness proof which leads to the construction of minimal canonical representatives for the equivalence classes of ; an "efficient" characterisation, based on a modified transition system. This characterisation seems promising for the development of automatedverification tools and also shows the callbyneed flavour of . Although in the...
Algebraic Theories for NamePassing Calculi
, 1996
"... In a theory of processes the names are atomic data items which can be exchanged and tested for identity. A wellknown example of a calculus for namepassing is the πcalculus, where names additionally are used as communication ports. We provide complete axiomatisations of late and early bisimulation ..."
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Cited by 48 (11 self)
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In a theory of processes the names are atomic data items which can be exchanged and tested for identity. A wellknown example of a calculus for namepassing is the πcalculus, where names additionally are used as communication ports. We provide complete axiomatisations of late and early bisimulation equivalences in such calculi. Since neither of the equivalences is a congruence we also axiomatise the corresponding largest congruences. We consider a few variations of the signature of the language; among these, a calculus of deterministic processes which is reminiscent of sequential functional programs with a conditional construct. Most of our axioms are shown to be independent. The axiom systems differ only by a few simple axioms and reveal the similarities and the symmetries of the calculi and the equivalences.
Presheaf Models for Concurrency
, 1999
"... In this dissertation we investigate presheaf models for concurrent computation. Our aim is to provide a systematic treatment of bisimulation for a wide range of concurrent process calculi. Bisimilarity is defined abstractly in terms of open maps as in the work of Joyal, Nielsen and Winskel. Their wo ..."
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Cited by 45 (19 self)
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In this dissertation we investigate presheaf models for concurrent computation. Our aim is to provide a systematic treatment of bisimulation for a wide range of concurrent process calculi. Bisimilarity is defined abstractly in terms of open maps as in the work of Joyal, Nielsen and Winskel. Their work inspired this thesis by suggesting that presheaf categories could provide abstract models for concurrency with a builtin notion of bisimulation. We show how
An Algebraic Verification of a Mobile Network
 Formal Aspects of Computing
, 1991
"... . In a mobile communication network some nodes change locations, and are therefore connected to different other nodes at different points in time. We show how some important aspects of such a network can be formally defined and verified using the \picalculus, which is a development of CCS (Calculus ..."
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Cited by 40 (1 self)
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. In a mobile communication network some nodes change locations, and are therefore connected to different other nodes at different points in time. We show how some important aspects of such a network can be formally defined and verified using the \picalculus, which is a development of CCS (Calculus of Communicating Systems) allowing port names to be sent as parameters in communication events. As an example of a mobile network we consider the Public Land Mobile Network currently being developed by the European Telecommunication Standards Institute and concentrate on the handover procedure which controls the dynamic topology of the network. 1. Introduction The need for mathematically rigorous definitions of communication protocol standards is today widely acknowledged. Such definitions are needed to specify protocols and services, and to verify that the protocols fulfil their services. Unfortunately most protocols still rely on informal definitions. One reason for this is that many aspec...
On Bisimulations for the Spi Calculus
 IN 9TH INTERNATIONAL CONFERENCE ON ALGEBRAIC METHODOLOGY AND SOFTWARE TECHNOLOGY
, 2002
"... The spi calculus is an extension of the pi calculus with cryptographic primitives, designed for the verification of cryptographic protocols. Due to the ..."
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Cited by 32 (3 self)
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The spi calculus is an extension of the pi calculus with cryptographic primitives, designed for the verification of cryptographic protocols. Due to the
History Dependent Automata
, 2001
"... In this paper we present historydependent automata (HDautomata in brief). They are an extension of ordinary automata that overcomes their limitations in dealing with historydependent formalisms. In a historydependent formalism the actions that a system can perform carry information generated i ..."
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Cited by 32 (9 self)
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In this paper we present historydependent automata (HDautomata in brief). They are an extension of ordinary automata that overcomes their limitations in dealing with historydependent formalisms. In a historydependent formalism the actions that a system can perform carry information generated in the past history of the system. The most interesting example is calculus: channel names can be created by some actions and they can then be referenced by successive actions. Other examples are CCS with localities and the historypreserving semantics of Petri nets. Ordinary