Results 1  10
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14
Decoding Choice Encodings
, 1999
"... We study two encodings of the asynchronous #calculus with inputguarded choice into its choicefree fragment. One encoding is divergencefree, but refines the atomic commitment of choice into gradual commitment. The other preserves atomicity, but introduces divergence. The divergent encoding is ..."
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Cited by 96 (5 self)
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We study two encodings of the asynchronous #calculus with inputguarded choice into its choicefree fragment. One encoding is divergencefree, but refines the atomic commitment of choice into gradual commitment. The other preserves atomicity, but introduces divergence. The divergent encoding is fully abstract with respect to weak bisimulation, but the more natural divergencefree encoding is not. Instead, we show that it is fully abstract with respect to coupled simulation, a slightly coarserbut still coinductively definedequivalence that does not enforce bisimilarity of internal branching decisions. The correctness proofs for the two choice encodings introduce a novel proof technique exploiting the properties of explicit decodings from translations to source terms.
Deriving Bisimulation Congruences in the DPO Approach to Graph Rewriting
, 2004
"... Motivated by recent work on the derivation of labelled transitions and bisimulation congruences from unlabelled reaction rules, we show how to solve this problem in the DPO (doublepushout) approach to graph rewriting. Unlike in previous approaches, we consider graphs as objects, instead of arrows, ..."
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Cited by 61 (10 self)
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Motivated by recent work on the derivation of labelled transitions and bisimulation congruences from unlabelled reaction rules, we show how to solve this problem in the DPO (doublepushout) approach to graph rewriting. Unlike in previous approaches, we consider graphs as objects, instead of arrows, of the category under consideration. This allows us to present a very simple way of deriving labelled transitions (called rewriting steps with borrowed context) which smoothly integrates with the DPO approach, has a very constructive nature and requires only a minimum of category theory. The core part of this paper is the proof sketch that the bisimilarity based on rewriting with borrowed contexts is a congruence relation.
NonInterleaving Semantics for Mobile Processes
 Theoretical Computer Science
, 1995
"... This paper studies causality in ßcalculus. Our notion of causality combines the dependencies given by the syntactic structure of processes with those originated by passing names. Our studies show that two transitions not causally related may however occur in a fixed ordering in any computation, i.e ..."
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Cited by 41 (19 self)
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This paper studies causality in ßcalculus. Our notion of causality combines the dependencies given by the syntactic structure of processes with those originated by passing names. Our studies show that two transitions not causally related may however occur in a fixed ordering in any computation, i.e., ßcalculus may implicitly express a precedence between actions. Our causality relation still induces the same partial order of transitions for all the computations that are obtained by shuffling transitions that are concurrent (i.e. related neither by causality nor by precedence). Other noninterleaving semantics are investigated and compared. The presentation takes advantage from a parametric definition of process behaviour given in an SOS style. All the results on bisimulationbased equivalences, congruences, axiomatizations and logics are taken (almost) without modifications from the interleaving theory. Finally, we extend our approach to higherorder ßcalculus, enriched with a spawn ...
Causality for Mobile Processes
 In Proceedings of ICALP'95, LNCS 944
, 1995
"... Abstract. We study causality in the ßcalculus. Our notion of causality combines the dependencies given by the syntactic structure of processes with those originated by passing names. It turns out that two transitions not causally related may although occur in a fixed ordering in any computation, i. ..."
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Cited by 29 (18 self)
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Abstract. We study causality in the ßcalculus. Our notion of causality combines the dependencies given by the syntactic structure of processes with those originated by passing names. It turns out that two transitions not causally related may although occur in a fixed ordering in any computation, i.e., ßcalculus may express implicitly a priority between actions. Our causality relation still induces the same partial order of transitions for all the computations that are obtained by shuffling transitions that are concurrent (= related neither by causality nor by priority). The presentation takes advantage from a parametric definition of process behaviour that highlights the essence of the topic. All the results on bisimulation based equivalences, congruences, axiomatizations and logics are taken (almost) for free from the interleaving theory. 1 Introduction The study of the behaviour of a distributed system may benefit from knowledge on the causal relation between its events. For examp...
Models for NamePassing Processes: Interleaving and Causal
 In Proceedings of LICS 2000: the 15th IEEE Symposium on Logic in Computer Science (Santa Barbara
, 2000
"... We study syntaxfree models for namepassing processes. For interleaving semantics, we identify the indexing structure required of an early labelled transition system to support the usual picalculus operations, defining Indexed Labelled Transition Systems. For noninterleaving causal semantics we de ..."
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Cited by 24 (3 self)
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We study syntaxfree models for namepassing processes. For interleaving semantics, we identify the indexing structure required of an early labelled transition system to support the usual picalculus operations, defining Indexed Labelled Transition Systems. For noninterleaving causal semantics we define Indexed Labelled Asynchronous Transition Systems, smoothly generalizing both our interleaving model and the standard Asynchronous Transition Systems model for CCSlike calculi. In each case we relate a denotational semantics to an operational view, for bisimulation and causal bisimulation respectively. We establish completeness properties of, and adjunctions between, categories of the two models. Alternative indexing structures and possible applications are also discussed. These are first steps towards a uniform understanding of the semantics and operations of namepassing calculi.
From Settheoretic Coinduction to Coalgebraic Coinduction: some results, some problems
, 1999
"... ..."
A Petri Net Semantics for piCalculus
 In Proc. CONCUR'95, volume 962 of LNCS
, 1995
"... . A distributed semantics for ßcalculus, based on P/T Petri nets with inhibitor arcs, is presented. This net semantics is sound w.r.t. the original early transition system semantics: the interleaving semantics of an agent p is retrievable from the net by considering the interleaving marking graph f ..."
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Cited by 9 (0 self)
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. A distributed semantics for ßcalculus, based on P/T Petri nets with inhibitor arcs, is presented. This net semantics is sound w.r.t. the original early transition system semantics: the interleaving semantics of an agent p is retrievable from the net by considering the interleaving marking graph for the associated marking dec(p). Furthermore, ßcalculus is equipped with a multistep and a causal semantics. The latter is compared with recent proposals appeared in the literature. 1 Introduction Distributed semantics for CCS and related languages based on (different classes of) Petri Nets have received a lot of attention in recent years (see, e.g., [5, 8, 10, 19], just to mention a few). The Place/Transition net semantics proposed in the literature can be classified into two main groups. The first one, we call locationoriented, exploits the syntactical structure of the process terms (notably, the parallel operator) to define their associated sets of places [5, 19]. The second one, we ...
A Graph Rewriting Semantics for the Polyadic πCalculus (Extended Version)
, 2000
"... We give a hypergraph rewriting semantics for the polyadic πcalculus, based on rewriting rules equivalent to those in the doublepushout approach. The structural congruence of the πcalculus is replaced by hypergraph isomorphism. The correctness of the encoding from the graphbased notation into πc ..."
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Cited by 5 (2 self)
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We give a hypergraph rewriting semantics for the polyadic πcalculus, based on rewriting rules equivalent to those in the doublepushout approach. The structural congruence of the πcalculus is replaced by hypergraph isomorphism. The correctness of the encoding from the graphbased notation into πcalculus can be shown by using an intermediate notation, socalled namebased graph terms, which form a bridge from graphs with explicit connections (by fusing nodes) to process calculi with implicit connections (by common channel names).
A Language for the Logical Specification of Processes and Relations
, 1996
"... We present L ß , a simple language that combines in an uniform way the reduction and stateoriented style of specification expected from a concurrent process calculus, with the more declarative and relational style of specification usual in logic programming. For the abstract operational semantics o ..."
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Cited by 4 (2 self)
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We present L ß , a simple language that combines in an uniform way the reduction and stateoriented style of specification expected from a concurrent process calculus, with the more declarative and relational style of specification usual in logic programming. For the abstract operational semantics of L ß two presentations are provided, a linear logic based proof system and a labelled transition system specification. We will argue that the present formulation of L ß can contribute to a better understanding of the relation between proofsearch and concurrency. We will also show that L ß is an expressive language both as a logic programming and as a process specification language. In particular, L ß can encode the full synchronous ßcalculus and a version of the hereditary Harrop formulas. 1 Introduction Due to its ability to handle resources in a finely controlled way, linear logic [13] was adopted as a prooftheoretic foundation of several logic programming and specification languages ...
Causality for Debugging Mobile Agents
 Acta Informatica
, 1996
"... Mobile agents, i.e. pieces of programs that can be sent around networks of computers, are starting to appear on the Internet. Such programs may be seen as an enrichment of traditional distributed computing. Since mobile agents may carry communication links with them as they move across the network, ..."
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Cited by 3 (2 self)
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Mobile agents, i.e. pieces of programs that can be sent around networks of computers, are starting to appear on the Internet. Such programs may be seen as an enrichment of traditional distributed computing. Since mobile agents may carry communication links with them as they move across the network, they create very dynamic interconnection structures that can be extremely complex to analyse. In this paper we study an example of a system based on the mobile agent principle written in the Facile programming language. We propose a Structural Operational Semantics (SOS) for Facile, giving a proved transition system that records encodings of the derivation trees of transitions in their labels. This information allows us to easily recover noninterleaving semantics for Facile by looking only at the labels of transitions. We use the new Facile semantics to debug an agent based system. This example is a scaled down version of a system demonstrated at the European IT Conference Exhibition in Brus...