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29
Timing and Causality in Process Algebra
 Acta Informatica
, 1992
"... . There has been considerable controversy in concurrency theory between the `interleaving' and `true concurrency' schools. The former school advocates associating a transition system with a process which captures concurrent execution via the interleaving of occurrences; the latter adopts more comple ..."
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Cited by 27 (0 self)
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. There has been considerable controversy in concurrency theory between the `interleaving' and `true concurrency' schools. The former school advocates associating a transition system with a process which captures concurrent execution via the interleaving of occurrences; the latter adopts more complex semantic structures to avoid reducing concurrency to interleaving. In this paper we show that the two approaches are not irreconcilable. We define a timed process algebra where occurrences are associated with intervals of time, and give it a transition system semantics. This semantics has many of the advantages of the interleaving approach; the algebra admits an expansion theorem, and bisimulation semantics can be used as usual. Our transition systems, however, incorporate timing information, and this enables us to express concurrency: merely adding timing appropriately generalises transition systems to asynchronous transition systems, showing that time gives a link between true concurrenc...
A Formal Semantics of Synchronous Interworkings
, 1993
"... this paper we present the formal semantics of interworkings in an algebraic framework. We concentrate on the main operators for combining interworkings: the interworking sequencing and the interworking merge. ..."
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Cited by 20 (9 self)
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this paper we present the formal semantics of interworkings in an algebraic framework. We concentrate on the main operators for combining interworkings: the interworking sequencing and the interworking merge.
Rooted branching bisimulation as a congruence
 Journal of Computer and System Sciences
, 2000
"... This article presents a congruence format, in structural operational semantics, for rooted branching bisimulation equivalence. The format imposes additional requirements on Groote’s ntyft format. It extends an earlier format by Bloom with standard notions such as recursion, iteration, predicates, an ..."
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Cited by 15 (6 self)
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This article presents a congruence format, in structural operational semantics, for rooted branching bisimulation equivalence. The format imposes additional requirements on Groote’s ntyft format. It extends an earlier format by Bloom with standard notions such as recursion, iteration, predicates, and negative premises. 1
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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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.
Formal Specification Languages in Knowledge and Software Engineering
 The Knowledge Engineering Review
, 1995
"... During the last years, a number of formal specification languages for knowledgebased systems (kbs) have been developed. Characteristics of such systems are a complex knowledge base and an inference engine which uses this knowledge to solve a given problem. Languages for kbs have to cover both th ..."
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Cited by 8 (5 self)
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During the last years, a number of formal specification languages for knowledgebased systems (kbs) have been developed. Characteristics of such systems are a complex knowledge base and an inference engine which uses this knowledge to solve a given problem. Languages for kbs have to cover both these aspects. They have to provide a means to specify a complex and large amount of knowledge and they have to provide a means to specify the dynamic reasoning behavior of a kbs. Nevertheless, kbs are just a specific type of software system. Therefore it seems quite natural to compare formal languages for specifying kbs with formal languages which were developed by the software engineering community for specifying software systems. That is the subject of this paper. Introduction Over the last few years a number of semiformal, formal, and executable specification languages 1 have been developed for describing knowledgebased systems (kbs). These specification languages can be used to ...
Operational and Denotational Semantics for the Box Algebra
 Theoretical Computer Science
, 1997
"... This paper describes general theory underpinning the operational semantics and the denotational Petri net semantics of the box algebra including recursion. For the operational semantics, inductive rules for process expressions are given. For the net semantics, a general mechanism of refinement and r ..."
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Cited by 8 (0 self)
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This paper describes general theory underpinning the operational semantics and the denotational Petri net semantics of the box algebra including recursion. For the operational semantics, inductive rules for process expressions are given. For the net semantics, a general mechanism of refinement and relabelling is introduced, using which the connectives of the algebra are defined. The paper also describes a denotational approach to the Petri net semantics of recursive expressions. A domain of nets is identified such that the solution of a given recursive equation can be found by fixpoint approximation from some suitable starting point. The consistency of the two semantics is demonstrated. The theory is generic for a wide class of algebraic operators and synchronisation schemes. Keywords: Petri nets, process algebra, refinement, denotational semantics, operational semantics, recursion, bisimulation.
The Box Algebra = Petri Nets + Process Expressions
, 1999
"... The paper describes a Petri net as well as a structural operational semantics for an algebra of process expressions. It specifically addresses this problem for the box algebra, a model of concurrent computation which combines Petri nets and standard process algebras. The main result is that it is po ..."
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Cited by 7 (0 self)
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The paper describes a Petri net as well as a structural operational semantics for an algebra of process expressions. It specifically addresses this problem for the box algebra, a model of concurrent computation which combines Petri nets and standard process algebras. The main result is that it is possible to obtain a framework where process expressions can be given two, entirely consistent, kinds of semantics: one based on Petri nets, the other on SOS rules. This consistency can also be extended to a partial order semantics. Keywords: Netbased algebraic calculi; relationships between net theory and other approaches; process algebras; box algebra; SOS semantics.
Characterising The Structure Of Simulation Models In CCS
, 1993
"... We describe how to apply the tools and techniques of process algebra to explore and verify the structure of simulation models. Process algebras are concise and precise objectoriented notations in which to express model structure and component interactions. We demonstrate how to specify the structur ..."
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Cited by 7 (7 self)
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We describe how to apply the tools and techniques of process algebra to explore and verify the structure of simulation models. Process algebras are concise and precise objectoriented notations in which to express model structure and component interactions. We demonstrate how to specify the structure and basic synchronisations of simulation models using Milner 's CCS (Calculus of Communicating Systems, see [14]) notation, and how to test for the consequences of a specification using the modal ¯ calculus [24]. In this way we open up the possibility of verifying from its static model description that a simulation model has certain basic desirable properties (is deadlock and livelock free and has appropriate safety, liveness and fairness characteristics [13]). Adopting these techniques from process algebra both makes models more reliable and saves a considerable amount of debugging time. Transactions of The Society for Computer Simulation, 10(3), October 193, 205236 1 Motivation I...
A Prototype Tool Set for Interworkings
 Philips Telecommunication Review
, 1993
"... this paper we give an overview of the language and discuss the prototype tool set which has been developed to support the use of interworkings. 1. Introduction ..."
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Cited by 6 (3 self)
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this paper we give an overview of the language and discuss the prototype tool set which has been developed to support the use of interworkings. 1. Introduction
A Comparison of Simulation Techniques and Algebraic Techniques for Verifying Concurrent Systems
 Formal Aspects of Computing
, 1997
"... Simulationbased assertional techniques and process algebraic techniques are two of the major methods that have been proposed for the verification of concurrent and distributed systems. It is shown how each of these techniques can be applied to the task of verifying systems described as input/output ..."
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Cited by 6 (1 self)
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Simulationbased assertional techniques and process algebraic techniques are two of the major methods that have been proposed for the verification of concurrent and distributed systems. It is shown how each of these techniques can be applied to the task of verifying systems described as input/output automata; both safety and liveness properties are considered. A small but typical circuit is verified in both of these ways, first using forward simulations, an execution correspondence lemma, and a simple fairness argument, and second using deductions within the process algebra DIOA for I/O automata. An extended evaluation and comparison of the two methods is given.