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Solos in concert
 IN ICALP’99, LNCS 1644:513–523
, 1999
"... We present a calculus of mobile processes without prefix or summation, and using two different encodings we show that it can express both action prefix and guarded summation. One encoding gives a strong correspondence but uses a match operator; the other yields a slightly weaker correspondence but u ..."
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Cited by 21 (4 self)
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We present a calculus of mobile processes without prefix or summation, and using two different encodings we show that it can express both action prefix and guarded summation. One encoding gives a strong correspondence but uses a match operator; the other yields a slightly weaker correspondence but uses no additional operators.
ProofChecking Protocols using Bisimulations
 IN PROC. CONCUR’99, LNCS 1664
, 1999
"... 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 def ..."
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Cited by 11 (2 self)
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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.
Observational Equivalence for Synchronized Graph Rewriting with Mobility
, 2001
"... We introduce a notion of bisimulation for graph rewriting systems, allowing us to prove observational equivalence for dynamically evolving graphs and networks. We use the framework of synchronized graph rewriting with mobility which we describe in two different, but operationally equivalent ways: on ..."
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Cited by 10 (6 self)
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We introduce a notion of bisimulation for graph rewriting systems, allowing us to prove observational equivalence for dynamically evolving graphs and networks. We use the framework of synchronized graph rewriting with mobility which we describe in two different, but operationally equivalent ways: on graphs defined as syntactic judgements and by using tile logic. One of the main results of the paper says that bisimilarity for synchronized graph rewriting is a congruence whenever the rewriting rules satisfy the basic source property. Furthermore we introduce an upto technique simplifying bisimilarity proofs and use it in an example to show the equivalence of a communication network and its specification.
Behavioural Equivalences for Dynamic Web Data
, 2004
"... We study behavioural equivalences for dynamic web data in Xd#, a model for reasoning about behaviour found in (for example) dynamic web page programming, applet interaction, and webservice orchestration. Xd# is based on an idealised model of semistructured data, and an extension of the #calculus ..."
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Cited by 6 (3 self)
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We study behavioural equivalences for dynamic web data in Xd#, a model for reasoning about behaviour found in (for example) dynamic web page programming, applet interaction, and webservice orchestration. Xd# is based on an idealised model of semistructured data, and an extension of the #calculus with locations and operations for interacting with data. The equivalences are nonstandard due to the integration of data and processes, and the presence of locations. Contents 1
Description and Verification of Mobile Processes with Graph Rewriting Techniques
"... The aim of this thesis is to describe the semantics of a process calculus by means of hypergraph rewriting, creating a specification mechanism combining modularity of process calculi and locality of graph transformation. Verification of processes is addressed by presenting two methods: barbed congru ..."
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Cited by 5 (4 self)
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The aim of this thesis is to describe the semantics of a process calculus by means of hypergraph rewriting, creating a specification mechanism combining modularity of process calculi and locality of graph transformation. Verification of processes is addressed by presenting two methods: barbed congruence for relating processes displaying the same behaviour and generic type systems, forming a central part of this work. Based on existing work in graph rewriting...
A πcalculus process semantics of concurrent idealised ALGOL
 In Proc. FOSSACS'99, volume 1578 of LNCS
, 1999
"... We study the use of the πcalculus for semantical descriptions of languages such as Concurrent Idealised ALGOL (CIA), combining imperative, functional and concurrent features. We first present an operational semantics for CIA, given by SOS rules and a contextual form of behavioural equivalence; th ..."
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Cited by 3 (0 self)
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We study the use of the πcalculus for semantical descriptions of languages such as Concurrent Idealised ALGOL (CIA), combining imperative, functional and concurrent features. We first present an operational semantics for CIA, given by SOS rules and a contextual form of behavioural equivalence; then a πcalculus semantics. As behavioural equivalence on πcalculus processes we choose the standard (weak early) bisimilarity. We compare the two semantics, demonstrating that there is a close operational correspondence between them and that the πcalculus semantics is sound. This allows for applying thecalculus theory in proving behavioural properties of CIA phrases. We discuss laws and examples which have served as benchmarks to various semantics, and a more complex example involving procedures of higher order.
On the Bisimulation Theory and Axiomatization of Higherorder Process Calculi
"... Higherorder process calculi, for its abstraction capability and theoretical significance, have constantly been receiving much attention in the field of process calculi, and stand as a mathematical tool for describing and analyzing mobile systems with dynamically changing interconnection structures ..."
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Higherorder process calculi, for its abstraction capability and theoretical significance, have constantly been receiving much attention in the field of process calculi, and stand as a mathematical tool for describing and analyzing mobile systems with dynamically changing interconnection structures. In this thesis we contribute to the higherorder paradigm in several aspects. • Higherorder πcalculus with mismatch: the bisimulation theory. Linear fragment of higherorder πcalculus with mismatch: the axiomatization. The problem of the axiomatization of higherorder process calculi, such as higherorder πcalculus, is always a nontrivial one. However, it is important, both in theory and practice, to be able to decide whether two higherorder processes are equivalent with respect to some bisimulation, which needs an algorithm that can effectively analyze and give an answer efficiently. We further the available work by considering the higherorder πcalculus with mismatch, which is a useful operator in bisimulation theory and especially the axiomatization, from algorithmic point of view. We first formulate the bisimulation theory, where the bisimulation we define is called open weak higherorder bisimulation, which is a nondelayed
Proving Write Invalidate Cache Coherence with Bisimulations in Isabelle/HOL
"... . The aim of this paper is to advocate the use of bisimulation relations in the verication of innitestate or parameterized systems, and demonstrates the support that generalpurpose theorem provers can oer. A powerful proof technique, known as up to expansion, is discussed and applied in a case stu ..."
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Cited by 2 (1 self)
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. The aim of this paper is to advocate the use of bisimulation relations in the verication of innitestate or parameterized systems, and demonstrates the support that generalpurpose theorem provers can oer. A powerful proof technique, known as up to expansion, is discussed and applied in a case study about write invalidate cache coherence. This example is of interest, as the system is parameterized in the number of its components, and the bisimulation relation reects the coherence of the caches with the main memory. 1 Introduction In recent years, generalpurpose theorem proving has come to play an important role in the verication of concurrent systems, especially for systems which are too large to be treated fully automatically, or even innite. Yet, if one is not to use the tool as a mere proof checker, some attention has to be spent on the choice of a suitable methodology. (1) Although generalpurpose theorem provers like Isabelle, PVS, or Coq, oer a considerable amount of au...
On the Mechanized Verification of Infinite Systems
"... Observation equivalence is a wellknown technique for proving that a concurrent system satises its specication. We report on our experience in the mechanization of observation equivalence proofs with the help of a generalpurpose theorem prover. Several casestudies are considered, incluiding an ..."
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Observation equivalence is a wellknown technique for proving that a concurrent system satises its specication. We report on our experience in the mechanization of observation equivalence proofs with the help of a generalpurpose theorem prover. Several casestudies are considered, incluiding an sliding window and a cachecoherence protocol. In all cases the system has an innite number of states, and sometimes also an arbitrarily large number of components. We show how compositionality and bisimulationupto techniques can be applied to reduce the size of the proofs. 1 Introduction One of the main goals of the A3 Teilprojekt within the Sonderforschungsbereich 342 is the development of verication techniques for distributed systems. Since 1995, special emphasis has been put on automatic (modelchecking) and semiautomatic techniques, and in the period 19982000, A3 has devoted special attention and resources to the development of machine support for the analysis of systems ...
On Efficiency Preorders ⋆
"... Abstract. Theories of efficiency preorders and precongruences for concurrent systems have been described in various papers. We describe a procedure to implement two of these precongruences. Considering the extra information that is needed to be maintained while computing efficiency preorders, our pr ..."
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Abstract. Theories of efficiency preorders and precongruences for concurrent systems have been described in various papers. We describe a procedure to implement two of these precongruences. Considering the extra information that is needed to be maintained while computing efficiency preorders, our procedure with a complexity O(n 3 m), compares favourably with that for deciding observational equivalence (O(n α m)). Further, the algorithm may be plugged in to existing modelcheckers such as the ConcurrencyWorkbench of the New Century (CWBNC) without any significant overheads of space or time. 1