M. Hansen, J. Kleist, and H. H#ttel. Bisimulations for asynchronous mobile processes. In Proceedings of the Tbilisi Symposium on Language, Logic, and Computation, 1995. Research paper HCRC/RP-72, Human Communication Research Centre, University of Edinburgh.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....appears to depend on having no output prexing. It does not depend on having asynchronous, rather than synchronous, bisimulation (see [3] for a study of insensitivity to name instantiation for various forms of synchronous bisimulations) Forms of asynchronous calculus have also been studied in [7], but the bisimilarity used is the standard (synchronous) one. Part of our theory, in particular axioms and normal forms, is based on that in [7] Our formulation of asynchronous bisimulation has been recently used by Nestmann and Pierce [15] to prove the full abstraction of the above mentioned ....

....a study of insensitivity to name instantiation for various forms of synchronous bisimulations) Forms of asynchronous calculus have also been studied in [7] but the bisimilarity used is the standard (synchronous) one. Part of our theory, in particular axioms and normal forms, is based on that in [7]. Our formulation of asynchronous bisimulation has been recently used by Nestmann and Pierce [15] to prove the full abstraction of the above mentioned encoding of input guarded choice. The paper is organized as follows. In section 2 we provide the basic denitions. In section 3 we present various ....

[Article contains additional citation context not shown here]

M. Hansen, J. Kleist, and H. H#ttel. Bisimulations for asynchronous mobile processes. In Proceedings of the Tbilisi Symposium on Language, Logic, and Computation, 1995. Research paper HCRC/RP-72, Human Communication Research Centre, University of Edinburgh.

....asynchrony strongly relies on the fact that sending messages to channel managers is always possible. Our point of view is that asynchronous communications are more realistic assumptions for distributed systems; thus we model them as (first class) language primitives. The variants of calculus [33, 34, 11, 26, 2] and that of CCS described in [42] model output actions as processes, and use bisimulation based equivalences to obtain observational semantics. We have followed a similar approach; output actions are modelled by means of internal moves that can always take place (i.e. are non blocking) and ....

M. Hansen, H. Huttel, J. Kleist. Bisimulations for Asynchronous Mobile Processes. Proc. of the Tbilisi Symposium on Languages, Logic and Computation 1995, also appeared as Research Paper HCRC/RP-72, Univ. of Edinburgh.

....which have some syntactic limitations on matching, sum or output prex. We are only aware of two congruence results for ground bisimulation: interleaving) ground bisimulation has been proved to be a congruence relation 1. in the subcalculus without matching and with only asynchronous outputs [4, 14]; 2. in I, a subcalculus of the calculus without matching and with only bound outputs [15] Both results are obtained by restraining the output construct. They do not show, however, the necessity of these limitations. For instance, one might hope to achieve the same results by forbidding ....

....Q 0 s.t. Q = a( e b) Gamma Q 0 and for all ec there is Q 00 s.t. Q 0 f ec = e bg = Q 00 and P 0 f ec = e bg R Q 00 . We use the symbols g ; la ; e and o for the weak versions of ground, late, early and open bisimulation, respectively. It was proved, independently in [4] and [14] developing an earlier result by Honda [5] that in absence of matching and of continuation underneath the output prex, ground bisimulation is a congruence. 1 A key lemma for proving the congruence of ground bisimulation is its closure under substitutions. Lemma 2.3 Relations g and ....

M. Hansen, H. H#ttel, and J. Kleist. Bisimulations for asynchronous mobile processes. In Proc. Tbilisi Symposium on Language, Logic, and Computation, 1996. Also available as BRICS Report No. EP-95HHK, Aalborg University, Denmark 1996.

....which have some syntactic limitations on matching, sum or output prefix. We are only aware of two congruence results for ground bisimulation: interleaving) ground bisimulation has been proved to be a congruence relation 1. in the subcalculus without matching and with only asynchronous outputs [4, 14]; 2. in I, a subcalculus of the calculus without matching and with only bound outputs [15] Both results are obtained by restraining the output construct. They do not show, however, the necessity of these limitations. For instance, one might hope to achieve the same results by forbidding ....

....exists Q 0 s.t. Q = a( e b) Gamma Q 0 and for all ec there is Q 00 s.t. Q 0 f ec = e bg = Q 00 and P 0 f ec = e bg R Q 00 . We use the symbols g ; la ; e and o for the weak versions of ground, late, early and open bisimulation, respectively. It was proved, independently in [4] and [14] developing an earlier result by Honda [5] that in absence of matching and of continuation underneath the output prefix, ground bisimulation is a congruence. 1 A key lemma for proving the congruence of ground bisimulation is its closure under substitutions. Lemma 2.3 Relations g ....

M. Hansen and J. Kleist and H. Huttel. Bisimulations for asynchronous mobile processes. in Proceedings of the Tbilisi Symposium on Language, Logic, and Computation. Research paper HCRC/RP-72, Human Communication Research Centre, University of Edinburgh. 1995.

....of out(a) is simple: the sender sends the message a and then waits for the acknowledgement from the TS; hence, the emission of a message is realized by means of a synchronous hand shake communication between the sender and the TS. This approach has already received an operational treatment in [HKH95, CGZ96, BGZ98]. ffl Unordered: The emission and the rendering of one message are distinct autonomous actions. Hence, out(a) P emits message a becoming the agent hhaiijP in one (internal) step, where P is free to proceed, but message a is not yet present in the TS; indeed, hhaii takes one further internal step ....

M. Hansen, J. Kleist, and H. H uttel. Bisimulations for Asynchronous Mobile Processes. Tech. Report, Basic Research in Computer Science, BRICS RS-96-8, 1996.

....which have some syntactic limitations on matching, sum or output prex. We are only aware of two congruence results for ground bisimulation: interleaving) ground bisimulation has been proved to be a congruence relation 1. in the subcalculus without matching and with only asynchronous outputs [4, 14]; 2. in I, a subcalculus of the calculus without matching and with only bound outputs [15] Both results are obtained by restraining the output construct. They do not show, however, the necessity of these limitations. For instance, one might hope to achieve the same results by forbidding ....

....Q 0 s.t. Q = a( e b) Gamma Q 0 and for all ec there is Q 00 s.t. Q 0 f ec = e bg = Q 00 and P 0 f ec = e bg R Q 00 . We use the symbols g ; la ; e and o for the weak versions of ground, late, early and open bisimulation, respectively. It was proved, independently in [4] and [14] developing an earlier result by Honda [5] that in absence of matching and of continuation underneath the output prex, ground bisi mulation is a congruence. 1 A key lemma for proving the congruence of ground bisimulation is its closure under substitutions. Lemma 2.3 Relations g and ....

M. Hansen and J. Kleist and H. H#ttel. Bisimulations for asynchronous mobile processes. in Proceedings of the Tbilisi Symposium on Language, Logic, and Computation. Research paper HCRC/RP-72, Human Communication Research Centre, University of Edinburgh. 1995.

....appears to depend on having no output prexing. It does not depend on having asynchronous, rather than synchronous, bisimulation (see [BS96] for a study of insensitivity to name instantiation for various forms of synchronous bisimulations) Forms of asynchronous calculus have also been studied in [HKH95], but the bisimilarity used is the standard (synchronous) one. Part of our theory, in particular axioms and normal forms, is related to that in [HKH95] Our formulation of asynchronous bisimulation has been recently used by Nestmann and Pierce [NP96] to prove the full abstraction of the ....

....of insensitivity to name instantiation for various forms of synchronous bisimulations) Forms of asynchronous calculus have also been studied in [HKH95] but the bisimilarity used is the standard (synchronous) one. Part of our theory, in particular axioms and normal forms, is related to that in [HKH95]. Our formulation of asynchronous bisimulation has been recently used by Nestmann and Pierce [NP96] to prove the full abstraction of the above mentioned encoding of input guarded choice. The paper is organized as follows. In section 2 we provide the basic denitions. In section 3 we present various ....

[Article contains additional citation context not shown here]

M. Hansen, J. Kleist, and H. H#ttel. Bisimulations for asynchronous mobile processes. In Proceedings of the Tbilisi Symposium on Language, Logic, and Computation, 1995. Research paper HCRC/RP-72, Human Communication Research Centre, University of Edinburgh.

....to show that for each s 2 A there is r 2 B s.t. t(s) v A t(r) by which the thesis will follows thanks to the law C2. But this fact follows by Lemmas 5.4 and 5.8. 2 16 6 The asynchronous calculus In this section we discuss the extensions of our theory to the asynchronous variant of calculus [23, 11, 20, 1]. 6.1 Syntax and semantics We presuppose a countable set N of names ranged over by a; b; x; y : Processes are ranged over by P; Q; R; The syntax of asynchronous calculus contains the operators of output action, guarded summation, restriction, parallel composition, matching ....

.... calculus is left open. There is then a substantial deal of work on bisimulation for ACCS or asynchronous calculus. A definition of asynchronous bisimulation for the calculus was first put forward in [24] while the first paper to face axiomatization problems for this language was [20], to the best of our knowledge. In [1] Amadio, Castellani and Sangiorgi offer a characterization of asynchronous calculus bisimilarity which avoids the infinitary operational semantics of Honda and Tokoro. Furthermore, the strong ( sensitive) version of bisimilarity is axiomatized. Both [35] and ....

M. Hansen, H. Huttel, J. Kleist. Bisimulations for Asynchronous Mobile Processes. In Proc. of the Tblisi Symposium on Language, Logic, and Computation, 1995. Also available as Research paper HCRC/RP-72, Human Communication Research Centre, University of Edimburgh.

....a. Constraint (a) ensures that all inputs at a are in P and can be statically detected. We may also say that restriction (a) denes the location of a, and see L as a simple calculus of distributed objects. Studies of bisimulation based behavioural equivalences for asynchronous mobile calculi are [17, 19, 15, 4]. In these theories, the most important algebraic law that is not in the theory of the synchronous calculus is a(x) ax = 0 Although this law is useful (it is used for instance by Pierce and Nestmann to prove the correctness of an encoding of guarded sum [29] it seems fair to say the ....

M. Hansen, H. H#ttel, and J. Kleist. Bisimulations for asynchronous mobile processes. In Proc. Tbilisi Symposium on Language, Logic, and Computation, 1996. Also available as BRICS Report No. EP-95-HHK, BRICS, Aalborg University, Denmark 1996.

....of out(a) is simple: the sender sends the message a and then waits for the acknowledgement from the TS; hence, the emission of a message is realized by means of a synchronous hand shake communication between the sender and the TS. This approach has already received an operational treatment in [HKH95,CGZ96,BGZ98]. ffl Unordered: The emission and the rendering of one message are distinct autonomous actions. Hence, out(a) P emits message a becoming the agent hhaiijP in one (internal) step, where P is free to proceed, but message a is not yet present in the TS; indeed, hhaii takes one further internal step ....

M. Hansen, J. Kleist, and H. Huttel. Bisimulations for Asynchronous Mobile Processes. Tech. Report, Basic Research in Computer Science, BRICS RS-96-8, 1996.

....channel and asynchrony strongly relies on the fact that sending messages to channel managers is always possible. Our point of view is that asynchronous communications are more realistic assumptions for distributed systems; thus we model them as language primitives. The variants of calculus [35, 36, 11, 28, 2] and that of CCS described in [44] model output actions as processes, and use bisimulation based equivalences to obtain observational semantics. We have followed a similar approach; output actions are modelled by means of internal moves which can always be performed (i.e. are non blocking) and ....

M. Hansen, H. Huttel, J. Kleist. Bisimulations for Asynchronous Mobile Processes. Proc. of the Tbilisi Symposium on Languages, Logic and Computation 1995, also appeared as Research Paper HCRC/RP-72, Univ. of Edimburgh.

....for each s 2 A there is r 2 B s.t. t(s) v A t(r) by which the thesis will follows thanks to the law G v G G 0 . But this fact follows by Lemma 4.4 and absorption Lemma 4.8. 2 5 The calculus In this section we discuss the extensions of our theory to the asynchronous variant of calculus [15, 8, 13, 1]. 5.1 Syntax and semantics A countable set N of names is ranged over by a; b; Processes are ranged over by P , Q and R. The syntax of asynchronous calculus contains the operators of inaction, output action, guarded summation, restriction, parallel composition, matching and ....

....[4] CSP [16] and LOTOS [20] follow the first approach and introduce explicit buffers in correspondence of output channels. This makes outputs non blocking and immediately executable. Within the same group we can place the work on the actors foundation [3] The asynchronous variants of calculus [15, 8, 13, 1] and CCS [19, 12, 9] follow the second approach, as they model output prefix a:P as a parallel composition a j P . In the past, all these formalisms have been equipped with observational semantics based on bisimulation or failures, but very few denotational or equational characterizations have ....

M. Hansen, H. Huttel, J. Kleist. Bisimulations for Asynchronous Mobile Processes. In Proc. of the Tblisi Symposium on Language, Logic, and Computation, 1995.

....of out(a) is simple: the sender sends the message a and then waits for the acknowledgement from the TS; hence, the emission of a message is realized by means of a synchronous hand shake communication between the sender and the TS. This approach has already received an operational treatment in [HKH95,CGZ96,BGZ98]. ffl Unordered: The emission and the rendering of one message are distinct autonomous actions. Hence, out(a) P emits message a becoming the agent hhaiijP in one (internal) step, where P is free to proceed, but message a is not yet present in the TS; indeed, hhaii takes one further internal step ....

M. Hansen, J. Kleist, and H. Huttel. Bisimulations for Asynchronous Mobile Processes. Tech. Report, Basic Research in Computer Science, BRICS RS-96-8, 1996.

....of out(a) is simple: the sender sends the message a and then waits for the acknowledgement from the TS; hence, the emission of a message is realized by means of a synchronous hand shake communication between the sender and the TS. This approach has already received an operational treatment in [HKH95] and [CGZ96] Unordered: The emission and the rendering of one message are distinct autonomous actions. Hence, out(a) P emits message a becoming the agent hhaiijP in one (internal) step, where P is free to proceed, but message a is not yet present in the TS; indeed, hhaii takes one further ....

M. Hansen, J. Kleist, and H. Huttel. Bisimulations for Asynchronous Mobile Processes. In Proc. Tbilisi Symposium on Language, Logic, and Computation, 1995.

....available for the potential partners. In this way, the order of emission is respected by the rendering order. The implementation of out(a) is simpler: the sender sends the message a and then waits for the acknowledgement from the TS. This approach has already received an operational treatment in [HKH95] and [CGZ96] Finally, according to the unordered semantics, proposed in [BGZ97b] the emission and the rendering of one message are distinct autonomous actions. The operation out(a) is implemented as a send operation of message a to the TS. As in distributed systems no precise knowledge of the ....

M. Hansen, J. Kleist, and H. H uttel. Bisimulations for Asynchronous Mobile Processes. In Proc. of the Tbilisi Symposium on Language, Logic, and Computation, 1995.

....by all process constructs. The remedy is here to require that matching transitions must match under all name substitutions. Since then, a number of subcalculi have been identified for which the four notions of bisimilarity coincide. Most importantly, this is case for the asynchronous # calculus [2, 4, 3]. Here, a process does not continue after an output action. Moreover, Sangiorgi has identified a private # calculus where the equivalences coincide. In the private # calculus , any output action must output a fresh name. In [1] Boreale and Sangiorgi consider the problem of giving a labelled ....

Martin Hansen, Hans Huttel, and Josva Kleist. Bisimulations for asynchronous mobile processes. In Insup Lee and Scott A. Smolka, editors, Proceedings of CONCUR '95, volume 962 of LNCS. Springer, 1995.

....extended version of the cal culus with a special case construct, which basically amounts to an extended matching operator. As the target calculus for our translation we instead go for as simple a version of the calculus as possible. The version that we shall use is the asynchronous calculus [CS96, Bou92, HT91, HK95]. The syntax of asynchronous calculus is in the present paper given by: P : a b j P jP j ( a)P j G j G G : 0 j a( b) P j :P j G G We let a; b; 2 Names range over an infinite c ountable set of names, b denote tuples of names, a tuple of the names a, b and c will be written ....

....and the process (ab j P ) The use of asynchronous communication has several advantages. Most importantly, several of the versions of bisimulation equivalence, that are distinct in the synchronous setting, coincide in an asynchronous setting. As a consequence, the algebraic theory becomes simpler [HK95, CS96]. For simplicity we shall only present the semantics of the monadic cal culus, but it is easily extended to handle the polyadic case. The semantics is given by a labelled transition system with labels: ff : xy j x(y) j xy xy denotes the output of the free name y on the name x. ....

Martin Hansen Hans Huttel and Josva Kleist. Bisimulations for asynchronous mobile processes. In Proceedings of the Tbilisi Symposium on Language, Logic and Computation, 1995.

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M. Hansen, J. Kleist, and H. H#ttel. Bisimulations for asynchronous mobile processes. In Proceedings of the Tbilisi Symposium on Language, Logic, and Computation, 1995. Research paper HCRC/RP-72, Human Communication Research Centre, University of Edinburgh.

No context found.

M. Hansen, H. Huttel, J. Kleist. Bisimulations for Asynchronous Mobile Processes. In Proc. of the Tblisi Symposium on Language, Logic, and Computation, 1995. Also available as Research paper HCRC/RP-72, Human Communication Research Centre, University of Edimburgh.

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