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14
Reactive Systems, Barbed Semantics, and the Mobile Ambients
"... Reactive systems, proposed by Leifer and Milner, represent a metaframework aimed at deriving behavioral congruences for those specification formalisms whose operational semantics is provided by rewriting rules. Despite its applicability, reactive systems suffered so far from two main drawbacks. Fir ..."
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Cited by 22 (6 self)
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Reactive systems, proposed by Leifer and Milner, represent a metaframework aimed at deriving behavioral congruences for those specification formalisms whose operational semantics is provided by rewriting rules. Despite its applicability, reactive systems suffered so far from two main drawbacks. First of all, no technique was found for recovering a set of inference rules, e.g. in the socalled SOS style, for describing the distilled observational semantics. Most importantly, the efforts focussed on strong bisimilarity, tackling neither weak nor barbed semantics. Our paper addresses both issues, instantiating them on a calculus whose semantics is still in a flux: Cardelli and Gordon’s mobile ambients. While the solution to the first issue is tailored over our case study, we provide a general framework for recasting (weak) barbed equivalence in the reactive systems formalism. Moreover, we prove that our proposal captures the behavioural semantics for mobile ambients proposed by Rathke and Sobociński and by Merro and Zappa Nardelli.
On the Construction of Sorted Reactive Systems
 IN PROCEEDINGS OF CONCUR’08, LNCS
, 2008
"... We develop a theory of sorted bigraphical reactive systems. Every application of bigraphs in the literature has required an extension, a sorting, of pure bigraphs. In turn, every such application has required a redevelopment of the theory of pure bigraphical reactive systems for the sorting at hand. ..."
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We develop a theory of sorted bigraphical reactive systems. Every application of bigraphs in the literature has required an extension, a sorting, of pure bigraphs. In turn, every such application has required a redevelopment of the theory of pure bigraphical reactive systems for the sorting at hand. Here we present a general construction of sortings. The constructed sortings always sustain the behavioural theory of pure bigraphs (in a precise sense), thus obviating the need to redevelop that theory for each new application. As an example, we recover Milner’s local bigraphs as a sorting on pure bigraphs. Technically, we give our construction for ordinary reactive systems, then lift it to bigraphical reactive systems. As such, we give also a construction of sortings for ordinary reactive systems. This construction is an improvement over previous attempts in that it produces smaller and much more natural sortings, as witnessed by our recovery of local bigraphs as a sorting.
M.: Dbtk: A toolkit for directed bigraphs
, 2009
"... Abstract. We present DBtk, a toolkit for Directed Bigraphs. DBtk supports a textual language for directed bigraphs, the graphical visualization of bigraphs, the calculation of IPO labels, and the calculation of redex matchings. Therefore, this toolkit provides the main functions needed to implement ..."
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Cited by 3 (0 self)
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Abstract. We present DBtk, a toolkit for Directed Bigraphs. DBtk supports a textual language for directed bigraphs, the graphical visualization of bigraphs, the calculation of IPO labels, and the calculation of redex matchings. Therefore, this toolkit provides the main functions needed to implement simulators and verification tools. 1
Computation in the Informatic Jungle
, 2010
"... Informatics bridges Turingcomputation and interactive behaviour; examples of the latter include ubiquitous/pervasive and biological systems. But how does a model of computation fit within a model of less disciplined informatic behaviour? This paper offers a precise treatment of that relationship, i ..."
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Cited by 2 (2 self)
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Informatics bridges Turingcomputation and interactive behaviour; examples of the latter include ubiquitous/pervasive and biological systems. But how does a model of computation fit within a model of less disciplined informatic behaviour? This paper offers a precise treatment of that relationship, identifying a class of calculational bigraphical reactive systems. We show how such a system contain a confluent calculation submodel, and how calculation only ever enables, never prevents, informatic behaviour of the larger model. We submit these results as a modest but essential beginning of a unified informatic theory.
MFPS 2008 A categorical model of the Fusion calculus
"... We provide a categorical presentation of the Fusion calculus. Working in a suitable category of presheaves, we describe the syntax as initial algebra of a signature endofunctor, and the semantics as coalgebras of a “behaviour ” endofunctor. To this end, we first give a new, congruencefree presentat ..."
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We provide a categorical presentation of the Fusion calculus. Working in a suitable category of presheaves, we describe the syntax as initial algebra of a signature endofunctor, and the semantics as coalgebras of a “behaviour ” endofunctor. To this end, we first give a new, congruencefree presentation of the Fusion calculus; then, the behaviour endofunctor is constructed by adding in a systematic way a notion of “state ” to the intuitive endofunctor induced by the LTS. Coalgebras can be given a concrete presentation as “stateful indexed labelled transition systems”; the bisimilarity over these systems is a congruence, and corresponds to hyperequivalence. Then, we model the labelled transition system of Fusion by as abstract categorical rules. As a consequence, we get a semantics for the Fusion calculus which is both compositional and fully abstract: two processes have the same semantics iff they are bisimilar, that is, hyperequivalent. 1
www.elsevier.com/locate/entcs An Algebra for Directed Bigraphs ⋆
"... We study the algebraic structure of directed bigraphs, a bigraphical model of computations with locations, connections and resources previously introduced as a unifying generalization of other variants of bigraphs. We give a sound and complete axiomatization of the (pre)category of directed bigraphs ..."
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We study the algebraic structure of directed bigraphs, a bigraphical model of computations with locations, connections and resources previously introduced as a unifying generalization of other variants of bigraphs. We give a sound and complete axiomatization of the (pre)category of directed bigraphs. Using this axiomatization, we give an adequate encoding of the Fusion calculus, showing the utility of the added directness. Keywords: Bigraphical models, categorical metamodels for Concurrency, fusion calculus. 1
Saturated LTSs for Adhesive Rewriting Systems
, 2010
"... GReactive Systems (GRSs) are a framework for the derivation of labelled transition systems (LTSs) from a set of unlabelled rules. A label for a transition from A to B is a context C[−] such that C[A] may perform a reaction and reach B. If either all contexts, or just the “minimal” ones, are conside ..."
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GReactive Systems (GRSs) are a framework for the derivation of labelled transition systems (LTSs) from a set of unlabelled rules. A label for a transition from A to B is a context C[−] such that C[A] may perform a reaction and reach B. If either all contexts, or just the “minimal” ones, are considered, the resulting LTS is called saturated (GIPO, respectively). The borrowed contexts (BCs) technique addresses the issue in the setting of the DPO approach. Indeed, from an adhesive rewriting system (ARS) a GRS can be defined such that DPO derivations correspond to reactions, and BC derivations to transitions of the GIPO LTS. This paper extends the BCs technique in order to derive saturated LTSs for ARSs, applying it to capture bisimilarity for asynchronous calculi.
Abstract TERMGRAPH 2007 An Algebra for Directed Bigraphs ⋆
"... We study the algebraic structure of directed bigraphs, a bigraphical model of computations with locations, connections and resources previously introduced as a unifying generalization of other variants of bigraphs. We give a sound and complete axiomatization of the (pre)category of directed bigraphs ..."
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We study the algebraic structure of directed bigraphs, a bigraphical model of computations with locations, connections and resources previously introduced as a unifying generalization of other variants of bigraphs. We give a sound and complete axiomatization of the (pre)category of directed bigraphs. Using this axiomatization, we give an adequate encoding of the Fusion calculus, showing the utility of the added directness.