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81
Transition systems, link graphs and Petri nets
, 2004
"... A framework is defined within which reactive systems can be studied formally. The framework is based upon scategories, a new variety of categories, within which reactive systems can be set up in such a way that labelled transition systems can be uniformly extracted. These lead in turn to behavi ..."
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Cited by 26 (5 self)
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A framework is defined within which reactive systems can be studied formally. The framework is based upon scategories, a new variety of categories, within which reactive systems can be set up in such a way that labelled transition systems can be uniformly extracted. These lead in turn to behavioural preorders and equivalences, such as the failures preorder (treated elsewhere) and bisimilarity, which are guaranteed to be congruential. The theory rests upon the notion of relative pushout previously introduced by the authors. The framework
A theoretical basis of communicationcentred concurrent programming
, 2006
"... This document presents two different paradigms of description of communication behaviour, one focussing on global message flows and another on endpoint behaviours, as formal calculi based on session types. The global calculus originates from Choreography Description Language, a web service descript ..."
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Cited by 26 (9 self)
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This document presents two different paradigms of description of communication behaviour, one focussing on global message flows and another on endpoint behaviours, as formal calculi based on session types. The global calculus originates from Choreography Description Language, a web service description language developed by W3C WSCDL working group. The endpoint calculus is a typed πcalculus. The global calculus describes an interaction scenario from a vantage viewpoint; the endpoint calculus precisely identifies a local behaviour of each participant. After introducing the static and dynamic semantics of these two calculi, we explore a theory of endpoint projection which defines three principles for wellstructured global description. The theory then defines a translation under the three principles which is sound and complete in the sense that all and only behaviours specified in the global description are realised as communications among endpoint processes. Throughout the theory, underlying type structures play a fundamental role. The document is divided in two parts: part I introduces the two descriptive frameworks using simple but nontrivial examples; the second part establishes a theory of the global and endpoint formalisms.
Bigraphical Reactive Systems: Basic Theory
 PROCEEDINGS OF THE INTERNATIONAL CONFERENCE OF MATHEMATICIANS
, 2001
"... A notion of bigraph is proposed as the basis for a model of mobile interaction. A bigraph consists of two independent structures: a topograph representing locality and a monograph representing connectivity. Bigraphs are equipped with reaction rules to form bigraphical reactive systems (BRSs), which ..."
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Cited by 25 (6 self)
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A notion of bigraph is proposed as the basis for a model of mobile interaction. A bigraph consists of two independent structures: a topograph representing locality and a monograph representing connectivity. Bigraphs are equipped with reaction rules to form bigraphical reactive systems (BRSs), which include versions of the calculus and the ambient calculus. Bigraphs are shown to be a special case of a more abstract notion, wide reactive systems (WRSs), not assuming any particular graphical or other structure but equipped with a notion of width, which expresses that agents, contexts and reactions may all be widely distributed entities. A behavioural theory is established for WRSs using the categorical notion of relative pushout; it allows labelled transition systems to be derived uniformly, in such a way that familiar behavioural preorders and equivalences, in particular bisimilarity, are congruential under certain conditions. Then the theory of bigraphs is developed, and they are shown to meet these conditions. It is shown that, using certain functors, other WRSs which meet the conditions may also be derived; these may, for example, be forms of BRS with additional structure. Simple examples of bigraphical systems are discussed; the theory is developed in a number of ways in preparation for deeper application studies.
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.
Bisimilarity of Open Terms
, 2000
"... Traditionally, in process calculi, relations over open terms, i.e., terms with free process variables, are defined as extensions of closedterm relations: two open terms are related if and only if all their closed instantiations are related. Working in the context of bisimulation, in this paper we s ..."
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Cited by 20 (0 self)
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Traditionally, in process calculi, relations over open terms, i.e., terms with free process variables, are defined as extensions of closedterm relations: two open terms are related if and only if all their closed instantiations are related. Working in the context of bisimulation, in this paper we study a different approach; we define semantic models for open terms, socalled conditional transition systems, and define bisimulation directly on those models. It turns out that this can be done in at least two different ways, one giving rise to De Simone's formal hypothesis bisimilarity and the other to a variation which we call hypothesispreserving bisimilarity (denoted t fh and t hp, respectively). For open terms, we have (strict) inclusions t fh /t hp / t ci (the latter denoting the standard ``closed instance' ' extension); for closed terms, the three coincide. Each of these relations is a congruence in the usual sense. We also give an alternative characterisation of t hp in terms of nonconditional transitions, as substitutionclosed bisimilarity (denoted t sb). Finally, we study the issue of recursion congruence: we prove that each of the above relations is a congruence with respect to the recursion operator; however, for t ci this result holds under more restrictive conditions than for tfh and thp.]
Typing mobility in the Seal Calculus
 IN CONCUR 2001, NUMBER 2154 IN LNCS
, 2001
"... The issue of this work is how to type mobility, in the sense that we tackle the problem of typing not only mobile agents but also their movement. This yields higherorder types for agents. To that end we first provide a new definition of the Seal Calculus that gets rid of existing inessential featur ..."
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Cited by 20 (4 self)
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The issue of this work is how to type mobility, in the sense that we tackle the problem of typing not only mobile agents but also their movement. This yields higherorder types for agents. To that end we first provide a new definition of the Seal Calculus that gets rid of existing inessential features while preserving the distinctive characteristics of the Seal model. Then we discuss the use of interfaces to type agents and define the type system. This type system induces a new interpretation of the types: interfaces describe interaction effects rather than, as it is customary, provided services. We discuss at length the difference of the two interpretations and justify our choice of the former.
A congruence format for namepassing calculi
 In Proceedings of the Second Workshop on Structural Operational Semantics (SOS’05), volume 156 of Electron. Notes Theor. Comput. Sci
, 2005
"... ..."
Solo Diagrams
 PROCEEDINGS OF TACS 2001
, 2001
"... We address the problems of implementing the
replication operator efficiently in the solos calculusa calculus of
mobile processes without prefix. This calculus is expressive enough to
admit an encoding of the whole fusion calculus and thus the
picalculus.
We show that nested occurrences of replic ..."
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Cited by 14 (2 self)
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We address the problems of implementing the
replication operator efficiently in the solos calculusa calculus of
mobile processes without prefix. This calculus is expressive enough to
admit an encoding of the whole fusion calculus and thus the
picalculus.
We show that nested occurrences of replication can be avoided, that
the size of replicated terms can be limited to three particles, and
that the usual unfolding semantics of replication can be replaced by
three simple reduction rules. To illustrate the results and show how
the calculus can be efficiently implemented we present a graphic
representation of agents in the solos calculus, adapting ideas from
interaction diagrams and pinets.
Reactive systems over directed bigraphs
 Proc. CONCUR 2007, Lecture Notes in Computer Science 4703 (2007
, 2007
"... Abstract. We study the construction of labelled transition systems from reactive systems defined over directed bigraphs, a computational metamodel which subsumes other variants of bigraphs. First we consider wide transition systems whose labels are all those generated by the IPO construction; the c ..."
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Cited by 14 (3 self)
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Abstract. We study the construction of labelled transition systems from reactive systems defined over directed bigraphs, a computational metamodel which subsumes other variants of bigraphs. First we consider wide transition systems whose labels are all those generated by the IPO construction; the corresponding bisimulation is always a congruence. Then, we show that these LTSs can be simplified further by restricting to a subclass of labels, which can be characterized syntactically. We apply this theory to the Fusion calculus: we give an encoding of Fusion in directed bigraphs, and describe its simplified wide transition system and corresponding bisimulation. 1
Dfusion: a distinctive fusion calculus
 In Proc. of APLAS04, volume 3302 of LNCS
, 2004
"... Abstract. Fusion calculus is commonly regarded as a generalisation of picalculus. Actually, we prove that there is no uniform fully abstract embedding of picalculus into Fusion. This fact motivates the introduction of a new calculus, DFusion, with two binders, λ and ν. We show that DFusion is str ..."
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Cited by 14 (2 self)
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Abstract. Fusion calculus is commonly regarded as a generalisation of picalculus. Actually, we prove that there is no uniform fully abstract embedding of picalculus into Fusion. This fact motivates the introduction of a new calculus, DFusion, with two binders, λ and ν. We show that DFusion is strictly more expressive than both picalculus and Fusion. The expressiveness gap is further clarified by the existence of a fully abstract encoding of mixed guarded choice into the choicefree fragment of DFusion. 1