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A Relational Model of NonDeterministic Dataflow
 In CONCUR'98, volume 1466 of LNCS
, 1998
"... . We recast dataflow in a modern categorical light using profunctors as a generalisation of relations. The well known causal anomalies associated with relational semantics of indeterminate dataflow are avoided, but still we preserve much of the intuitions of a relational model. The development fits ..."
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Cited by 27 (13 self)
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. We recast dataflow in a modern categorical light using profunctors as a generalisation of relations. The well known causal anomalies associated with relational semantics of indeterminate dataflow are avoided, but still we preserve much of the intuitions of a relational model. The development fits with the view of categories of models for concurrency and the general treatment of bisimulation they provide. In particular it fits with the recent categorical formulation of feedback using traced monoidal categories. The payoffs are: (1) explicit relations to existing models and semantics, especially the usual axioms of monotone IO automata are read off from the definition of profunctors, (2) a new definition of bisimulation for dataflow, the proof of the congruence of which benefits from the preservation properties associated with open maps and (3) a treatment of higherorder dataflow as a biproduct, essentially by following the geometry of interaction programme. 1 Introduction A fundament...
Profunctors, open maps and bisimulation
 Mathematical Structures in Computer Science, To appear. Available from the Glynn Winskel’s web
, 2000
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Categorical Models for Fairness and a Fully Abstract Presheaf Semantics of SCCS with Finite Delay
 CTCS’99, LNCS
, 1999
"... We present a presheaf model for the observation of infinite as well as finite computations. We apply it to give a denotational semantics of SCCS with finite delay, in which the meanings of recursion are given by final coalgebras and meanings of finite delay by initial algebras of the process equatio ..."
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Cited by 6 (1 self)
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We present a presheaf model for the observation of infinite as well as finite computations. We apply it to give a denotational semantics of SCCS with finite delay, in which the meanings of recursion are given by final coalgebras and meanings of finite delay by initial algebras of the process equations for delay. This can be viewed as a first step in representing fairness in presheaf semantics. We give a concrete representation of the presheaf model as a category of generalised synchronisation trees and show that it is coreflective in a category of generalised transition systems, which are a special case of the general transition systems of Hennessy and Stirling. The open map bisimulation is shown to coincide with extended bisimulation of Hennessy and Stirling, which is essentially fair CTL*bisimulation. Finally we formulate Milners operation semantics of SCCS with finite delay in terms of generalised transition systems and prove that the presheaf semantics is fully abstract with respect to extended bisimulation.
Computer Science Journal of Moldova, vol.19, no.1(55), 2011 Architecting software concurrency
"... Nowadays, the majority of software systems are inherently concurrent. Anyway, internal and external concurrent activities increase the complexity of systems ’ behavior. Adequate architecting can significantly decrease implementation errors. This work is motivated by the desire to understand how conc ..."
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Nowadays, the majority of software systems are inherently concurrent. Anyway, internal and external concurrent activities increase the complexity of systems ’ behavior. Adequate architecting can significantly decrease implementation errors. This work is motivated by the desire to understand how concurrency can constrain or influence software architecting. As a result, in the paper a methodological architecting framework applied for systems with ”concurrencyintensive architecture ” is described. This special term is defined to emphasize architectures, in which concurrent interactions are crucial. Also in the paper potential models for each phase of architecting framework are indicated.
Tools
, 2005
"... The vision for the future, pervasive itsupport at our work places is that we can carry a mobile device anywhere allowing us seamlessly to cooperate, share information and coordinate tasks with our colleagues. A topical example is the electronic medical journals currently being developed. Workflow m ..."
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The vision for the future, pervasive itsupport at our work places is that we can carry a mobile device anywhere allowing us seamlessly to cooperate, share information and coordinate tasks with our colleagues. A topical example is the electronic medical journals currently being developed. Workflow management systems (WFMS) incorporated in most ERPsystems such as Microsoft Business Solutions Axapta are likely to play a central role for this vision to become true. Already early 2000 it was estimated that there were more than 200 suppliers worldwide offering standalone workflow management software [44] and in Denmark the largest 290 companies are expected to invest more than 4 billion Dkr during the next few years in ERP systems [18]. A workflow management system is a generic itsystem supporting coordination, resource allocation and analysis of the execution of business processes in organisations. In the current reference model for Workflow management systems (Figure 1), the core service is carried out by a socalled workflow engine on a central server. The workflow engine keeps track of the status and progress of active processes, referred to as active cases. Active cases are typically longlived, as e.g. the process initiated by the first consultation of a pregnant woman to the birth of the child at the hospital, and is therefore
Categorical Models for Fairness: Completion vs Delay
"... We study two different approaches to semantics for fairness within the categorical framework of presheaf models for concurrency [1, 2]. The first approach, used in e.g. dataflow models, is based on representing finite or infinite completed observations. A completed observation is the result of an in ..."
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We study two different approaches to semantics for fairness within the categorical framework of presheaf models for concurrency [1, 2]. The first approach, used in e.g. dataflow models, is based on representing finite or infinite completed observations. A completed observation is the result of an infinite computation. A finite completed observation is then the result of an infinite computation that only produces finitely many actions, i.e. at some point it stops producing output but stays active (as opposed to being deadlocked). The second approach is that of e.g. Milner's SCCS with finite delay [6], having an observable delay action and representing also finite incomplete observations, but only infinite completed observations. More precisely, we consider (separated) presheaves over respectively the category Comp = pf(Act ! [ Act ); pf ; of incomplete finite, and completed infinite and finite observations, and the category Inf = pf((Act [ f1g) ! ); pf ; of inc...