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24
Relations in Concurrency
"... The theme of this paper is profunctors, and their centrality and ubiquity in understanding concurrent computation. Profunctors (a.k.a. distributors, or bimodules) are a generalisation of relations to categories. Here they are first presented and motivated via spans of event structures, and the seman ..."
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Cited by 263 (33 self)
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The theme of this paper is profunctors, and their centrality and ubiquity in understanding concurrent computation. Profunctors (a.k.a. distributors, or bimodules) are a generalisation of relations to categories. Here they are first presented and motivated via spans of event structures, and the semantics of nondeterministic dataflow. Profunctors are shown to play a key role in relating models for concurrency and to support an interpretation as higherorder processes (where input and output may be processes). Two recent directions of research are described. One is concerned with a language and computational interpretation for profunctors. This addresses the duality between input and output in profunctors. The other is to investigate general spans of event structures (the spans can be viewed as special profunctors) to give causal semantics to higherorder processes. For this it is useful to generalise event structures to allow events which “persist.”
Refinement of Actions and Equivalence Notions for Concurrent Systems
 Acta Informatica
, 1998
"... This paper combines and extends the material of [GGa/c/d/e], except for the part in [GGc] on refinement of transitions in Petri nets and the discussion of TCSPlike parallel composition in [GGe]. An informal presentation of some basic ingredients of this paper appeared as [GGb]. Among others, th ..."
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Cited by 38 (1 self)
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This paper combines and extends the material of [GGa/c/d/e], except for the part in [GGc] on refinement of transitions in Petri nets and the discussion of TCSPlike parallel composition in [GGe]. An informal presentation of some basic ingredients of this paper appeared as [GGb]. Among others, the treatment of action refinement in stable and nonstable event structures is new. The research reported here was supported by Esprit project 432 (METEOR), Esprit Basic Research Action 3148 (DEMON), Sonderforschungsbereich 342 of the TU Munchen, ONR grant N0001492J1974 and the Human Capital and Mobility Cooperation Network EXPRESS (Expressiveness of Languages for Concurrency). Contents
History Dependent Automata
, 2001
"... In this paper we present historydependent automata (HDautomata in brief). They are an extension of ordinary automata that overcomes their limitations in dealing with historydependent formalisms. In a historydependent formalism the actions that a system can perform carry information generated i ..."
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Cited by 28 (8 self)
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In this paper we present historydependent automata (HDautomata in brief). They are an extension of ordinary automata that overcomes their limitations in dealing with historydependent formalisms. In a historydependent formalism the actions that a system can perform carry information generated in the past history of the system. The most interesting example is calculus: channel names can be created by some actions and they can then be referenced by successive actions. Other examples are CCS with localities and the historypreserving semantics of Petri nets. Ordinary
A Theory of Processes with Durational Actions
 Theoretical Computer Science
, 1994
"... s are available from the same host in the directory /pub/TR/UBLCS/ABSTRACTS in plain text format. All local authors can be reached via email at the address lastname@cs.unibo.it. UBLCS Technical Report Series 9315 Data Algorithm: A Numerical Method to Extract Shape Information from Gray Scale Ima ..."
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Cited by 20 (2 self)
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s are available from the same host in the directory /pub/TR/UBLCS/ABSTRACTS in plain text format. All local authors can be reached via email at the address lastname@cs.unibo.it. UBLCS Technical Report Series 9315 Data Algorithm: A Numerical Method to Extract Shape Information from Gray Scale Images, R. Davoli, F. Tamburini, June 1993. 9316 Towards Performance Evaluation in Process Algebras, R. Gorrieri, M. Roccetti, July 1993. 9317 Split and ST Bisimulation Semantics, R. Gorrieri, C. Laneve, July 1993. 9318 Multilanguage Interoperability, G. Attardi, M. Gaspari, July 1993. 9319 HERMES: an Expert System for the Prognosis of Hepatic Diseases, I. Bonf a, C. Maioli, F. Sarti, G.L. Milandri, P.R. Dal Monte, September 1993. 9320 An Information Flow Security Property for CCS, R. Focardi, R. Gorrieri, October 1993. 9321 A Classification of Security Properties, R. Focardi, R. Gorrieri, October 1993. 9322 Real Time Systems: A Tutorial, F. Panzieri, R. Davoli, October 1993. 93...
Axioms for Contextual Net Processes
 In Automata, Languages and Programming, volume 1443 of LNCS
, 1998
"... . In the classical theory of Petri nets, a process is an operational description of the behaviour of a net, which takes into account the causal links between transitions in a sequence of firing steps. In the categorical framework developed in [19, 11], processes of a P/T net are modeled as arrows of ..."
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Cited by 14 (9 self)
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. In the classical theory of Petri nets, a process is an operational description of the behaviour of a net, which takes into account the causal links between transitions in a sequence of firing steps. In the categorical framework developed in [19, 11], processes of a P/T net are modeled as arrows of a suitable monoidal category: In this paper we lay the basis of a similar characterization for contextual P/T nets, that is, P/T nets extended with read arcs, which allows a transition to check for the presence of a token in a place, without consuming it. 1 Introduction Petri nets [24] are probably the best studied and most used model for concurrent systems: Their range of applications covers a wide spectrum, from their use as a specification tool to their analysis as a suitable semantical domain. A recent extension to the classical model concerns a class of nets where transitions are able to check for the presence of a token in a place without actually consuming it. While the possibility ...
On Plain and Hereditary HistoryPreserving Bisimulation
, 1999
"... We investigate the difference between two wellknown notions of independence bisimilarity, historypreserving bisimulation and hereditary historypreserving bisimulation. We characterise the difference between the two bisimulations in tracetheoretical terms, advocating the view that the first i ..."
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Cited by 14 (5 self)
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We investigate the difference between two wellknown notions of independence bisimilarity, historypreserving bisimulation and hereditary historypreserving bisimulation. We characterise the difference between the two bisimulations in tracetheoretical terms, advocating the view that the first is (just) a bisimulation for causality, while the second is a bisimulation for concurrency. We explore the frontier zone between the two notions by defining a hierarchy of bounded backtracking bisimulations. Our goal
On Relating Some Models for Concurrency
 TAPSOFT'93: Theory and Practice of Software Development, volume 668 of Lecture Notes in Computer Science
, 1993
"... s are available from the same host in the directory /pub/TR/UBLCS/ABSTRACTS in plain text format. All local authors can be reached via email at the address lastname@cs.unibo.it. UBLCS Technical Report Series 931 Consistent Global States of Distributed Systems: Fundamental Concepts and Mechanism, ..."
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Cited by 13 (1 self)
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s are available from the same host in the directory /pub/TR/UBLCS/ABSTRACTS in plain text format. All local authors can be reached via email at the address lastname@cs.unibo.it. UBLCS Technical Report Series 931 Consistent Global States of Distributed Systems: Fundamental Concepts and Mechanism, by O. Babao glu and K. Marzullo, January 1993. 932 Understanding NonBlocking Atomic Commitment, by O. Babao glu and S. Toueg, January 1993. 933 Anchors and Paths in a Hypertext Publishing System, by C. Maioli and F. Vitali, February 1993. 934 A Formalization of Priority Inversion, by O. Babao glu, K. Marzullo and F. Schneider, March 1993. 935 Some Modifications to the Dexter Model for the Formal Description of Hypertexts, by S. Lamberti, C. Maioli and F. Vitali, April 1993. 936 Versioning Issues in a Collaborative Distributed Hypertext System, by C. Maioli, S. Sola and F. Vitali, April 1993. 937 Distributed Programming with Logic Tuple Spaces, by P. Ciancarini, April 1993. 938 Coord...
On the Expressiveness of higher dimensional automata
 EXPRESS 2004, ENTCS
, 2005
"... Abstract In this paper I compare the expressive power of several models of concurrency based on their ability to represent causal dependence. To this end, I translate these models, in behaviour preserving ways, into the model of higher dimensional automata, which is the most expressive model under i ..."
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Cited by 12 (0 self)
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Abstract In this paper I compare the expressive power of several models of concurrency based on their ability to represent causal dependence. To this end, I translate these models, in behaviour preserving ways, into the model of higher dimensional automata, which is the most expressive model under investigation. In particular, I propose four different translations of Petri nets, corresponding to the four different computational interpretations of nets found in the literature. I also extend various equivalence relations for concurrent systems to higher dimensional automata. These include the history preserving bisimulation, which is the coarsest equivalence that fully respects branching time, causality and their interplay, as well as the STbisimulation, a branching time respecting equivalence that takes causality into account to the extent that it is expressible by actions overlapping in time. Through their embeddings in higher dimensional automata, it is now welldefined whether members of different models of concurrency are equivalent.
Deciding and axiomatizing weak ST bisimulation for a process algebra with recursion and action refinement
 ACM Transactions on Computational Logic
, 2002
"... 1. INTRODUCTION ST semantics, originally defined in [van Glabbeek and Vaandrager 1987] over Petri Nets, is one of the most studied noninterleaving semantics. The main reason is that ST semantics is the less informative semantics that is a congruence for ..."
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Cited by 11 (4 self)
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1. INTRODUCTION ST semantics, originally defined in [van Glabbeek and Vaandrager 1987] over Petri Nets, is one of the most studied noninterleaving semantics. The main reason is that ST semantics is the less informative semantics that is a congruence for
Categorical Models for Concurrency: Independence, Fairness and Dataflow
 BRICS DISSERTATION SERIES DS001
, 2000
"... This thesis is concerned with formal semantics and models for concurrent computational systems, that is, systems consisting of a number of parallel computing sequential systems, interacting with each other and the environment. A formal semantics gives meaning to computational systems by describing t ..."
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Cited by 6 (4 self)
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This thesis is concerned with formal semantics and models for concurrent computational systems, that is, systems consisting of a number of parallel computing sequential systems, interacting with each other and the environment. A formal semantics gives meaning to computational systems by describing their behaviour in a mathematical model. For concurrent systems the interesting aspect of their computation is often how they interact with the environment during a computation and not in which state they terminate, indeed they may not be intended to terminate at all. For this reason they are often referred to as reactive systems, to distinguish them from traditional calculational systems, as e.g. a program calculating your income tax, for which the interesting behaviour is the answer it gives when (or if) it terminates, in other words the (possibly partial) function it computes between input and output. Church's thesis tells us that regardless of whether we choose the lambda calculus, Turing machines, or almost any modern programming language such as C or Java to describe calculational systems, we are able to describe exactly the same class of functions. However, there is no agreement on observable behaviour for concurrent reactive systems, and consequently there is no correspondent to Church's thesis. A result of this fact is that an overwhelming number of different and often competing notions of observable behaviours, primitive operations, languages and mathematical models for describing their semantics, have been proposed in the litterature on concurrency. The work