Victor, B., Parrow, J. Concurrent Constraints in the Fusion Calculus. In Proceedings of ICALP'98. LNCS vol 1443. Springer-Verlag. April 1998. URL: http://www.docs.uu.se/~victor/tr/ccfc.shtml  Home/Search   Document Not in Database   Summary   Related Articles   Check

....symmetric. Another important simplification is that there is only one sensible bisimulation equivalence. The present paper intends to give a brief overview of the fusion calculus. For a more comprehensive treatment, the reader is referred to Victor s Ph.D. thesis [V98] and related papers [VP98], PV98 1] and [PV98 2] Concurrent Constraint Programming As a motivation to the fusion calculus a reminder of the Concurrent Constraint Programming paradigm is presented. In Constraint Programming the central notion is that of a constraint. A constraint can be seen as a guard that must be ....

Victor, B., Parrow, J. Concurrent Constraints in the Fusion Calculus. In Proceedings of ICALP'98. LNCS vol 1443. Springer-Verlag. April 1998. URL: http://www.docs.uu.se/~victor/tr/ccfc.shtml

....we briefly illustrate the connection between our work and Yoshida s process graphs. 1 Introduction There are many calculi for describing interactive behaviour based on names, name abstraction and name restriction. Examples of such calculi include the # calculus [MPW92] the fusion calculus [VP98] (which aims to be more foundational than the # calculus and which does not use name abstraction) calculi for describing features in distributed systems such as the ambient calculus [CG98] and the distributed # calculus [Sew97] the spi calculus for analysing security protocols [AG97] and the ....

.... The first variant is the synchronous # calculus mentioned in the previous section (however we now embed it into a symmetric action calculus rather than a reflexive one) The second is the # I calculus of Sangiorgi [San96] and the third is a variant of the fusion calculus of Victor and Parrow [VP98] which we call the #F calculus. The three calculi di#er in the binding of their input and output processes: the # calculus binds on the input process, the # I calculus binds on both input and output processes, and the #F calculus binds on neither. Processes in the three algebras are generated ....

B. Victor and J. Parrow. Concurrent constraints in the fusion calculus. In Proceedings of ICALP'98, number 1443 in Lecture Notes in Computer Science, pages 455--469. Springer-Verlag, 1998. 22

....to replace abstracted names in the input process; this replacement is represented with a substitution. In contrast a #F reaction is directionless and fuses names; this is recorded with an explicit fusion. The #F calculus is similar in many respects to the fusion calculus of Parrow and Victor [10, 13], and to the chi calculus of Fu [1] These calculi also have a directionless reaction which fuses names. The difference is in how the name fusions have effect. In the fusion calculus, fusions occur implicitly within the reaction relation and their effect is immediate. In the #F calculus, fusions ....

B. Victor and J. Parrow. Concurrent constraints in the fusion calculus. In ICALP, LNCS 1443. Springer, 1998.

....we brie y illustrate the connection between our work and Yoshida s process graphs. 1 Introduction There are many calculi for describing interactive behaviour based on names, name abstraction and namerestriction. Examples of such calculi include the calculus [MPW92] the fusion calculus [VP98] (which aims to be more foundational than the calculus and which does not use name abstraction) calculi for describing features in distributed systems such as the ambient calculus [CG98] and the distributed calculus [Sew97] the spi calculus for analysing security protocols [AG97] and the ....

.... The rst variant is the synchronous calculus mentioned in the previous section (however we now embed it into a symmetric action calculus rather than a re exive one) The second is the I calculus of Sangiorgi [San96] and the third is a variant of the fusion calculus of Victor and Parrow [VP98] which we call the F calculus. The three calculi di er in the binding of their input and output processes: the calculus binds on the input process, the I calculus binds on both input and output processes, and the F calculus binds on neither. Processes in the three algebras are generated ....

B. Victor and J. Parrow. Concurrent constraints in the fusion calculus. In Proceedings of ICALP'98, number 1443 in Lecture Notes in Computer Science, pages 455-469. Springer-Verlag, 1998.

....unclear what a polyadic update like [a=x; b=x] should mean. In contrast, the polyadic fusion fa = x; b = xg is unproblematic: it is just the equivalence equating all of a; b and x. The fusion calculus has a higher degree of symmetry and this has profound implications for our technical proofs. In [21] we explore the weak version of the equivalence defined in the present paper, give a reduction semantics of the fusion calculus, and show how to encode three variants of the ae calculus [9] a foundational calculus for concurrent constraints. Another way to obtain an input output symmetry is in ....

B. Victor and J. Parrow. Concurrent constraints in the fusion calculus. In Proceedings of ICALP'98, LNCS. Springer, 1998. URL: http://www.docs.uu. se/~victor/tr/ccfc.html. 10

....In this paper we shall study the theory of weak bisimulation equivalence. The main idea is that the internal action 1 needs not be simulated. This can be expressed formally in different ways, leading to different weak equivalences. To find the most appropriate one we use the barbed equivalence in [VP98]. This means that we define an observation predicate (corresponding to the ability to observe the ports where communications occur) and a reduction relation (corresponding to internal transitions 1 Gamma ) In CCS the resulting congruence becomes observation congruence, and in the calculus it ....

....unsound) The rest of the paper is organized as follows. In Section 2 we recapitulate the syntax and semantics of the fusion calculus, and in Section 3 the definition of hyperequivalence and its algebraic theory. The paper is formally self contained but a reader is referred to our previous papers [PV97, VP98] for explanations and motivations. In Section 4 we recall the definition of weak hyperbisimulation, and there the original contribution of the present paper starts. We define weak hypercongruence and prove it is the largest congruence in weak hyperequivalence (this is analogous to observation ....

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B. Victor and J. Parrow. Concurrent constraints in the fusion calculus. Accepted for publication in the Proc. of ICALP'98. Available from http://www.docs.uu.se/~victor/tr/ccfc.html, Jan. 1998. 18

....we show that it can express both action prefix and guarded summation. One encoding gives a strong correspondence but uses a match operator; the other yields a slightly weaker correspondence but uses no additional operators. 1 Introduction The fusion calculus was introduced by Parrow and Victor [15, 20, 16] as a simplification and extension of the calculus [6] The simplification is easy to see: there is only one binding operator where has two; input and output are completely symmetric which they are not in ; and it has only one sensible bisimulation congruence where has three. The extension ....

....agrees with fex = e yg; ran(oe) e z = and dom(oe) e z P Gamma P 0 P j Q Gamma P 0 j Q P Gamma P 0 (x)P Gamma (x)P 0 P j Q Q Gamma Q 0 Q 0 j P 0 P Gamma P 0 Table 1. Reduction rules for the fusion calculus of solos. For examples and motivations we refer the reader to [15, 20, 16]. 2.3 Equivalence and Preorder We will use the standard idea of barbed bisimulation developed by Milner and Sangiorgi [7] in the setting of CCS, further investigated in a calculus setting by Sangiorgi [17] and later used in many other calculi as an intuitive observational equivalence. The idea ....

B. Victor and J. Parrow. Concurrent constraints in the fusion calculus. In K. G. Larsen, S. Skyum, and G. Winskel, editors, Proc. of ICALP '98, volume 1443 of LNCS, pages 455--469. Springer, July 1998.

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