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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 303 (36 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.”
PartialOrder Reduction in Symbolic State Space Exploration
, 1997
"... . State space explosion is a fundamental obstacle in formal verification of designs and protocols. Several techniques for combating this problem have emerged in the past few years, among which two are significant: partialorder reductions and symbolic state space search. In asynchronous systems, ..."
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Cited by 63 (0 self)
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. State space explosion is a fundamental obstacle in formal verification of designs and protocols. Several techniques for combating this problem have emerged in the past few years, among which two are significant: partialorder reductions and symbolic state space search. In asynchronous systems, interleavings of independent concurrent events are equivalent, and only a representative interleaving needs to be explored to verify local properties. Partialorder methods exploit this redundancy and visit only a subset of the reachable states. Symbolic techniques, on the other hand, capture the transition relation of a system and the set of reachable states as boolean functions. In many cases, these functions can be represented compactly using binary decision diagrams (BDDs). Traditionally, the two techniques have been practiced by two different schoolspartialorder methods with enumerative depthfirst search for the analysis of asynchronous network protocols, and symbolic bread...
A Logical Study of Distributed Transition Systems
, 1995
"... We extend labelled transition systems to distributed transition systems by labelling the transition relation with a finite set of actions, representing the fact that the actions occur as a concurrent step. We design an actionbased temporal logic in which one can explicitly talk about steps. The log ..."
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Cited by 34 (5 self)
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We extend labelled transition systems to distributed transition systems by labelling the transition relation with a finite set of actions, representing the fact that the actions occur as a concurrent step. We design an actionbased temporal logic in which one can explicitly talk about steps. The logic is studied to establish a variety of positive and negative results in terms of axiomatizability and decidability. Our positive results show that the step notion is amenable to logical treatment via standard techniques. They also help us to obtain a logical characterization of two well known models for distributed systems: labelled elementary net systems and labelled prime event structures. Our negative results show that demanding deterministic structures when dealing with a "noninterleaved " notion of transitions is, from a logical standpoint, very expressive. They also show that another well known model of distributed systems called asynchronous transition systems exhibits a surprising a...
Synchronizations in Team Automata for Groupware Systems
 Journal of Collaborative Computing
, 1999
"... Team automata have been proposed in (Ellis, 1997) as a formal framework for modeling both the conceptual and the architectural level of groupware systems. Here we define team automata in a mathematically precise way in terms of component automata which synchronize on certain executions of actions. A ..."
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Cited by 31 (11 self)
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Team automata have been proposed in (Ellis, 1997) as a formal framework for modeling both the conceptual and the architectural level of groupware systems. Here we define team automata in a mathematically precise way in terms of component automata which synchronize on certain executions of actions. At the conceptual level, our model serves as a formal framework in which basic groupware notions can be rigorously defined and studied. At the architectural level, team automata can be used as building blocks in the design of groupware systems.
Relationships between Models of Concurrency
, 1994
"... . Models for concurrency can be classified with respect to three relevant parameters: behaviour/system, interleaving/noninterleaving, linear/branching time. When modelling a process, a choice concerning such parameters corresponds to choosing the level of abstraction of the resulting semantics. The ..."
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Cited by 26 (4 self)
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. Models for concurrency can be classified with respect to three relevant parameters: behaviour/system, interleaving/noninterleaving, linear/branching time. When modelling a process, a choice concerning such parameters corresponds to choosing the level of abstraction of the resulting semantics. The classifications are formalized through the medium of category theory. Keywords. Semantics, Concurrency, Models for Concurrency, Categories. Contents 1 Preliminaries 431 2 Deterministic Transition Systems 433 3 Noninterleaving vs. Interleaving Models 436 Synchronization Trees and Labelled Event Structures : : : : : : : : : : : : : : 438 Transition Systems with Independence : : : : : : : : : : : : : : : : : : : : : : 439 4 Behavioural, Linear Time, Noninterleaving Models 441 Semilanguages and Event Structures : : : : : : : : : : : : : : : : : : : : : : : 443 Trace Languages and Event Structures : : : : : : : : : : : : : : : : : : : : : : 446 5 Transition Systems with Independence and Lab...
Overcoming Heterophobia: Modeling Concurrency in Heterogeneous Systems
 Application of Concurrency to System Design
, 2001
"... We describe a framework where formal models can be rigorously defined and compared, and their interconnections can be unambiguously specified. We use trace algebra and trace structure algebra to provide the underlying mathematical machinery. We believe that this framework will be essential to provid ..."
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Cited by 23 (8 self)
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We describe a framework where formal models can be rigorously defined and compared, and their interconnections can be unambiguously specified. We use trace algebra and trace structure algebra to provide the underlying mathematical machinery. We believe that this framework will be essential to provide the foundations of an intermediate format that will provide the Metropolis infrastructure with a formal mechanism for interoperability among tools and specification methods.
Models for Concurrency: Towards a Classification
 Theoretical Computer Science
, 1996
"... Models for concurrency can be classified with respect to three relevant parameters: behaviour/system, interleaving/noninterleaving, linear/branching time. When modelling a process, a choice concerning such parameters corresponds to choosing the level of abstraction of the resulting semantics. In thi ..."
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Cited by 21 (0 self)
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Models for concurrency can be classified with respect to three relevant parameters: behaviour/system, interleaving/noninterleaving, linear/branching time. When modelling a process, a choice concerning such parameters corresponds to choosing the level of abstraction of the resulting semantics. In this paper, we move a step towards a classification of models for concurrency based on the parameters above. Formally, we choose a representative of any of the eight classes of models obtained by varying the three parameters, and we study the formal relationships between using the language of category theory.
Synthesizing Distributed Transition Systems From Global Specifications
, 1999
"... We study the problem of synthesizing distributed implementations from global specifications. In particular, we characterize when a global transition system can be implemented as a synchronized product of local transition systems. Our work extends a number of previous studies in this area which h ..."
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Cited by 20 (0 self)
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We study the problem of synthesizing distributed implementations from global specifications. In particular, we characterize when a global transition system can be implemented as a synchronized product of local transition systems. Our work extends a number of previous studies in this area which have tended to make strong assumptions about the specificationeither in terms of determinacy or in terms of information concerning concurrency.
Formal Verification of Safety Properties in Timed Circuits
, 2000
"... The incorporation of timing makes circuit verification computationally expensive. This paper proposes a new approach for the verification of timed circuits. Rather than calculating the exact timed state space, a conservative overestimation that fulfills the property under verification is derived. Ti ..."
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Cited by 17 (6 self)
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The incorporation of timing makes circuit verification computationally expensive. This paper proposes a new approach for the verification of timed circuits. Rather than calculating the exact timed state space, a conservative overestimation that fulfills the property under verification is derived. Timing analysis with absolute delays is efficiently performed at the level of event structures and transformed into a set of relative timing constraints. With this approach, conventional symbolic techniques for reachability analysis can be efficiently combined with timing analysis. Moreover, the set of timing constraints used to prove the correctness of the circuit can also be reported for backannotation purposes. Some preliminary results obtained by a naive implementation of the approach show that systems with more than 10^6 untimed states can be verified.