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Process algebra for synchronous communication
 Inform. and Control
, 1984
"... Within the context of an algebraic theory of processes, an equational specification of process cooperation is provided. Four cases are considered: free merge or interleaving, merging with communication, merging with mutual exclusion of tight regions, and synchronous process cooperation. The rewrite ..."
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Cited by 412 (57 self)
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Within the context of an algebraic theory of processes, an equational specification of process cooperation is provided. Four cases are considered: free merge or interleaving, merging with communication, merging with mutual exclusion of tight regions, and synchronous process cooperation. The rewrite system behind the communication algebra is shown to be confluent and terminating (modulo its permutative reductions). Further, some relationships are shown to hold between the four concepts of merging. © 1984 Academic Press, Inc.
Concurrent Transition Systems
 Theoretical Computer Science
, 1989
"... : Concurrent transition systems (CTS's), are ordinary nondeterministic transition systems that have been equipped with additional concurrency information, specified in terms of a binary residual operation on transitions. Each CTS C freely generates a complete CTS or computation category C , ..."
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Cited by 40 (5 self)
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: Concurrent transition systems (CTS's), are ordinary nondeterministic transition systems that have been equipped with additional concurrency information, specified in terms of a binary residual operation on transitions. Each CTS C freely generates a complete CTS or computation category C , whose arrows are equivalence classes of finite computation sequences, modulo a congruence induced by the concurrency information. The categorical composition on C induces a "prefix" partial order on its arrows, and the computations of C are conveniently defined to be the ideals of this partial order. The definition of computations as ideals has some pleasant properties, one of which is that the notion of a maximal ideal in certain circumstances can serve as a replacement for the more troublesome notion of a fair computation sequence. To illustrate the utility of CTS's, we use them to define and investigate a dataflowlike model of concurrent computation. The model consists of machines, which ...
Computations, residuals and the power of indeterminacy
 In Timo Lepisto and Arto Salomaa, editors, Proceedings of the Fifteenth ICALP
, 1988
"... We investigate the power of Katmstyle datattow networks, with processes that may exhibit indeterminate behavior. Our main result is a theorem about networks of "monotone " processes, which shows: (1) that the input/output relation of such a network is a total and monotone relation; and (2 ..."
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Cited by 20 (10 self)
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We investigate the power of Katmstyle datattow networks, with processes that may exhibit indeterminate behavior. Our main result is a theorem about networks of "monotone " processes, which shows: (1) that the input/output relation of such a network is a total and monotone relation; and (2) every relation that is total, monotone, and continuous in a certain sense, is the input/output relation of such a network. Now, the class of monotone networks includes networks that compute arbitrary continuous inpu*~/output functions, an "angelic merge " network, and an "ilffinityfair merge " network that exhibits countably indeterminate branching. Since the "fair merge " relation is neither monotone nor continuous, a corollary of our main result is the impossibility of implementing fair merge in terms of continuous functions, angelic merge, and infinityfair merge. Our results are established by applying the powerftll technique of "residuals " to the computations of a network. Residuals, which have previously been used to investigate optimal reduction strategies for the Acalculus, have recently been demonstrated by one of the authors (Stark) "also to be of use in reasoning about concurrent systems. Here, we define the general notion of a "residual operation " on an automaton, and show how residual operations defined on the components of a network induce a certain preorder E on the set of computations of the network. For networks of "monotone port automata, " we show that the "fair " computations coincide with Xmaximal computations. Our results follow from this extremely convenient property. 1
The power of the future perfect in program logics
 Information and Control
, 1985
"... The expressiveness of branching time tense (temporal) logics whose eventually operators are relativised to general paths into the future is investigated. These logics are interpreted in models obtained by generalising the usual notion of transition system to allow infinite transitions. It is shown t ..."
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Cited by 19 (0 self)
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The expressiveness of branching time tense (temporal) logics whose eventually operators are relativised to general paths into the future is investigated. These logics are interpreted in models obtained by generalising the usual notion of transition system to allow infinite transitions. It is shown that the presence of formulae expressing the future perfect enables one to prove that the expressiveness of the logic can be charaeterised by a notion of bisimulation on the generalised transition systems. The future perfect is obtained by adding a past tense operator to the language. Finally the power of various tense languages from the literature are
Concurrent Transition System Semantics of Process Networks
 In Fourteenth ACM Symposium on Principles of Programming Languages
, 1987
"... Using concurrent transition systems [Sta86], we establish connections between three models of concurrent process networks, Kahn functions, input /output automata, and labeled processes. For each model, we define three kinds of algebraic operations on processes: the product operation, abstractio ..."
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Cited by 9 (7 self)
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Using concurrent transition systems [Sta86], we establish connections between three models of concurrent process networks, Kahn functions, input /output automata, and labeled processes. For each model, we define three kinds of algebraic operations on processes: the product operation, abstraction operations, and connection operations. We obtain homomorphic mappings, from input/output automata to labeled processes, and from a subalgebra (called "input/output processes") of labeled processes to Kahn functions. The proof that the latter mapping preserves connection operations amounts to a new proof of the "Kahn Principle." Our approach yields: (1) extremely simple definitions of the process operations; (2) a simple and natural proof of the Kahn Principle that does not require the use of "strategies" or "scheduling arguments"; (3) a semantic characterization of a large class of labeled processes for which the Kahn Principle is valid, (4) a convenient operational semantics...
Constructing Finite State Implementations of KnowledgeBased Programs with Perfect Recall (Extended Abstract)
 In Proceedings of the Conference on Foundations of Software Technology and Theoretical Computer Science, Springer LNCS No. 1180
, 1996
"... ) Ron van der Meyden Computing Science University of Technology, Sydney PO Box 123, Broadway NSW 2007 Australia email: ron@socs.uts.edu.au Abstract. Knowledgebased programs have been proposed as an abstract formalism for the design of multiagent protocols, based on the idea that an agent's a ..."
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Cited by 4 (1 self)
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) Ron van der Meyden Computing Science University of Technology, Sydney PO Box 123, Broadway NSW 2007 Australia email: ron@socs.uts.edu.au Abstract. Knowledgebased programs have been proposed as an abstract formalism for the design of multiagent protocols, based on the idea that an agent's actions are a function of its state of knowledge. The key questions in this approach concern the relationship between knowledgebased programs and their concrete implementations, in which the actions are a function of the agents' local states. In previous work we have shown that with respect to a perfect recall semantics for knowledge, finite state implementations of knowledgebased programs do not always exist. Indeed, determining the existence of such an implementation is undecidable. However, we also identified a sufficient condition under which the existence of a finite state implementation is guaranteed, although this sufficient condition is also undecidable. We show in this paper that there ...
Translations between Modal Logics of Reactive Systems
, 1994
"... We propose meaningpreserving translations between LB, LU and Lsb (three modal logics in full agreement with branching bisimulation), thus proving that they all have the same expressivity. The translations can be implemented and have potential applications in the automated analysis of reactive syste ..."
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Cited by 4 (0 self)
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We propose meaningpreserving translations between LB, LU and Lsb (three modal logics in full agreement with branching bisimulation), thus proving that they all have the same expressivity. The translations can be implemented and have potential applications in the automated analysis of reactive systems. In this work the main difficulty is that LB uses both forward and backward modalities, whereas LU and Lsb only have forward modalities. The technique we developed to cope with this, is an adaptation in a branchingtime framework of the methods underlying Gabbay's Separation Theorem for P T L [8]. This technique is powerful and has been applied successfully to related problems.
Verification of LOTOS Specifications using Term Rewriting Techniques
, 1994
"... Recently the use of formal methods in describing and analysing the behaviour of (computer) systems has become more common. This has resulted in the proliferation of a wide variety of different specification formalisms, together with analytical techniques and methodologies for specification developme ..."
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Cited by 2 (2 self)
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Recently the use of formal methods in describing and analysing the behaviour of (computer) systems has become more common. This has resulted in the proliferation of a wide variety of different specification formalisms, together with analytical techniques and methodologies for specification development. The particular specification formalism adopted for this study is LOTOS, an ISO standard formal description technique. Although there are many works dealing with how to write LOTOS specifications and how to develop a LOTOS specification from the initial abstract requirements specification to concrete implementation, relatively few works are concerned with the problems of expressing and proving the correctness of LOTOS specifications, i.e. verification. The main objective of this thesis is to address this shortfall by investigating the meaning of verification as it relates to concurrent systems in general, and in particular to those systems described using LOTOS. Further goals are to autom...
Logical Characterizations of Truly Concurrent Bisimulation
, 1994
"... We present two modal logics, interpreted over prime event structures without silent moves, that characterize historypreserving bisimulation. That is, two event structures satisfy the same formulae iff they are historypreserving bisimilar. These logics use pasttense modalities and pomsets observat ..."
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Cited by 1 (0 self)
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We present two modal logics, interpreted over prime event structures without silent moves, that characterize historypreserving bisimulation. That is, two event structures satisfy the same formulae iff they are historypreserving bisimilar. These logics use pasttense modalities and pomsets observations. Though quite different in form and spirit, the two logics turn out to have the same expressive power, in the sense that there exists a twoway translation between them. Keywords: Semantics of concurrency, modal logics for true concurrency, expressivity of modal logics. Introduction During the past decade, partial order semantics have been studied in depth as a promising approach to the semantic aspects of reactive systems [Gra81, GR83, Pra86]. In particular, causalitybased models enable one to formalize interesting features of systems' behaviors for which concurrency is no longer identified with sequential nondeterminism as it is in interleaving models. As it has been pointed out [...
!"#$%&'#()*#%&+,&./0)#1(&'*+1,*1 (1993), 2.3%&45&00%&161227 QUANTALES, OBSERVATIONAL LOGIC AND PROCESS SEMANTICS
"... Various notions of observing and testing processes are placed in a uniform algebraic framework in which observations are taken as constituting a quantale. General completeness criteria are stated, and proved in our applications. 2 67("/89:&",;&<+*91(8=&>)",#"318 ..."
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Various notions of observing and testing processes are placed in a uniform algebraic framework in which observations are taken as constituting a quantale. General completeness criteria are stated, and proved in our applications. 2 67("/89:&",;&<+*91(8=&>)",#"3185&.781(2"#+.,"3&3.?+*&",;&0(.*188&81/",#+*8 1.