U. Montanari and F. Rossi. True-concurrency in Concurrent Constraint Programming. In V. Saraswat and K. Ueda, editors, Proceedings of the 1991 International Symposium on Logic Programming, pages 694--716, San Diego, USA, 1991. The MIT Press.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....an appropriate metaphor to present the data is crucial. The model of data presentation proposed in this paper is derived from graph based visualization, as proposed by Carro and Hermengildo in [3] The graph metaphor was first formally introduced in constraint programming by Montanari and Rossi [11]. The contribution of this work is the development of different graph based views for correctness debugging constraint programs and the proposal of debugging methodologies based on these views for frequently occurring incorrect behavior of constraint programs. Furthermore, the techniques are ....

U. Montanari and F. Rossi. True concurrency in concurrent constraint programming. In V. Saraswat and K. Ueda, editors, Proceedings of the 1991.

....an appropriate metaphor to present the data is crucial. The model of data presentation proposed in this paper is derived from graph based visualization, as proposed by Carro and Hermengildo in [2] The graph metaphor was first formally introduced in constraint programming by Montanari and Rossi [11]. The contribution of this work is the development of different graph based views for correctness debugging constraint programs and the proposal of debugging methodologies based on these views for frequently occurring incorrect behavior of constraint programs. Furthermore, we propose techniques ....

Ugo Montanari and Francesca Rossi. True concurrency in concurrent constraint programming. In Vijay Saraswat and Kazunori Ueda, editors, Proceedings of the 1991 International Symposium on Logic Programming, pages 694--713, San Diego, USA, June 1991. The MIT Press.

....possibility of interacting objects with predicates and functions within the unified graph rewriting framework should also be explored. Recently it has been shown that concurrent logic languages are instances of the wider family of constraint logic programming languages (Saraswat 1989) Moreover, Montanari and Rossi (1991) discuss the relationship of concurrent constraint logic programming and graph rewriting. A fruitful area of research is towards extending the work presented in this paper to provide graph rewriting based implementations of concurrent constraint logic languages. In addition, parallel logic ....

Montanari, U. and Rossi, F. (1991) True concurrency in concurrent constraint programming, in ISLP91, San Diego, USA, 28 October--1 November, MIT Press, Cambridge, MA, pp. 694--713.

....logically entail a given constraint (or its negation) now, then they always will. The same is true of the tell operation. Equivalently, the store monotonically accumulates information in the form of constraints on variables. We should also note that if the store is represented as a (hyper)graph [51], where the nodes are variables and the 16 It is possible to add implicit asks with a tell operation, creating a suspensive tell (The purpose is to facilitate the implementation of complex constraint systems over which a general constraint solver may not be possible) This is trivially ....

Ugo Montanari and Francesca Rossi. True-concurrency in concurrent constraint programming. In Vijay Saraswat and Kazunori Ueda, editors, Logic Programming Proceedings of the 1991 International Symposium, pages 694-- 716, London, England, 1991. Massachusetts Institute of Technology.

....interpretation and partial evaluation [1] We will conduct a systematic study of such a higher order extension of OSFstructures, both semantically and proof theoretically. True concurrency semantics for cc programs In the description of a cc program via the algebraic formalism for graph grammars [132], the store is a graph and both the agents and the entailment relation of the constraint system are described by a set of graph productions. More precisely, both agents and primitive constraints are represented as hyperarcs which connect some variables. Then, in order to give a true concurrency ....

....that makes graph grammars very suitable to express the causality information needed for a true concurrency semantics, since two productions can be applied concurrently when they intersect only in their interface graphs. However, we believe that the graph grammar representation of CCP proposed in [132] is only one of the possible ways in which cc programs can be faithfully modelled. Therefore, other context dependent formalism will be analyzed. Furthermore, applications to other execution frameworks of our true concurrency approach to the semantics of cc programs will be investigated. On of ....

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U. Montanari and F. Rossi. True-concurrency in concurrent constraint programming. In Proc. ILPS91, 1991.

....the possibility of interacting objects with predicates and functions within the unified graph rewriting framework should also be explored. Recently it has been shown that concurrent logic languages are instances of the wider family of constraint logic programming languages ( 41] Moreover, [42] discusses the relationship of concurrent constraint logic programming and graph rewriting. A fruitful area of research is towards extending the work presented in this paper to provide graph rewriting based implementations of concurrent constraint logic languages. In addition, parallel logic ....

U. Montanari and F. Rossi, True Concurrency in Concurrent Constraint Programming, ISLP'91, San Diego, USA, Oct. 28 - Nov. 1, MIT Press, pp. 694-713.

....not always easy to deduce from them how variables are related to each other, due to the lack of accuracy (inherent to the abstraction process) in the representation of the variables themselves. A different approach to abstracting the constraints in the store is to show them as a graph (see, e.g. MR91] for a formal presentation of such a graph) where variables are represented as nodes, and nodes are linked iff the corresponding variables are related by a constraint (Figure 18) 6 . This representation provides the programmer with an approximate understanding of the constraints are present in ....

U. Montanari and F. Rossi. True-concurrency in Concurrent Constraint Programming. In V. Saraswat and K. Ueda, editors, Proceedings of the 1991 International Symposium on Logic Programming, pages 694--716, San Diego, USA, 1991. The MIT Press.

No context found.

U. Montanari and F. Rossi. True concurrency in concurrent constraint programming. In Proc. ILPS. MIT Press, 1991.

....occurrence nets to give a semantics to cc program, these relations are then interpreted as describing, respectively, the temporal precedence, the possible simultaneity, and the nondeterministic choices among steps of cc computations. This semantics is a conservative extension of the one in [10, 11], since by restricting the obtained contextual net to subnets without mutual exclusion, we get essentially the partial orders defined in that semantics. What was missing there, and is now present in the semantics based on contextual nets, is that all the computations of a cc program are ....

....of a rewrite rule. There will be as many rewrite rules as the number of agents and declarations in a program (which is finite) plus the number of pairs of the entailment relation (which can be infinite) The role of such rewrite rules coincides with that of the graph productions used in [10, 11]. However, in this paper we choose to use a formalism which is simpler, while still retaining all the features of graph grammars which are necessary for our approach. Definition 1 (computation state) Given a program P = F:A with a constraint system hD; i, a state is a multiset of elements of ....

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U. Montanari and F. Rossi. True concurrency in concurrent constraint programming. In Proc. ILPS91. MIT Press, 1991.

....focussed on finding so called islands of tractability , that is, classes of constraint problems where one of the preprocessing algorithms is enough to solve the problem. Examples of some of the classes that have been identified are tree like problems, problems generated by graph grammars (Montanari and Rossi, 1991a) and problems with a certain relationship between their graph structure and their level of consistency (Dechter, 1992) This body of results and efficient algorithms made the field of constraint solving very attractive to application developers, which in fact took advantage of the constraint ....

....addition deletion, so that one has to look at only a (hopefully small) subpart of the problem while achieving arc consistency again. In the context of constraint abstraction, one may be interested only in finding the allowed values for some of the variables, non necessarily all (Dechter, 1990) (Montanari and Rossi, 1991a) This means finding the effect that the whole problem has on some of the variables only. This in general has the same complexity as finding a complete solution. However, some of the variables in the non interesting part of the problem can be found to be redundant if certain conditions are met, ....

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U. Montanari and F. Rossi. True concurrency in concurrent constraint programming. In Proc. ILPS91. MIT Press, 1991.

....4. 2 The abstract machine We have developed an abstract machine for cc programs, based on graphs and graph rewriting rules, which is able to express such homogeneity in a natural way, and also to exploit it for a better understanding of the level of concurrency implicitly contained in cc programs ([MR91d, MR92c]) One of the main features of such machine is that it is concurrent, while most of the computation models used for describing the dynamic behavior of cc programs are instead sequential and thus reduce concurrency to nondeterminism (that is, they cannot distinguish between computation steps which ....

U. Montanari and F. Rossi. True concurrency in concurrent constraint programming. In Proc. ILPS91. MIT Press, 1991.

....(that is, constraints) into the store. The semantics of CC programs is usually given following the SOS style operational semantics [18,19,3] and thus it suffers from the typical pathologies of an interleaving semantics. On the other hand, the concurrent semantics approach introduced in [11], which is equipped with a non monolithic model of the shared store and of its communication with the agents, allows to express uniformly the behavior of the store and that of the agents, and, as a consequence, to derive a semantic structure where it is possible and easy to see the maximal level ....

....optimizations which require knowledge about any one of these two concepts. In fact, an interleaving semantics is not able to express such knowledge correctly, mainly due to the fact that concurrency is not directly expressible but is instead reduced to nondeterminism. The concurrent semantics in [11] is based on an operational semantics described via context dependent rewrite rules, i.e. rules which have a left hand side, a right hand side, and a context. Each rule is applicable if both its left hand side and its context are present in the current state of the computation. A rule application ....

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U. Montanari and F. Rossi. True concurrency in concurrent constraint programming. In Proc. ILPS. MIT Press, 1991.

.... necessary to have a faithful description of the computations and their causal dependencies is the concurrent constraint programming framework [Sar93] where the fundamental operation of constraint asking can be modelled precisely by checking for the presence of a constraint in the common store [MR91]. In [MR92b] we model concurrent constraint programming via graph grammars, thus obtaining a trueconcurrency semantics where agents asking for the same constraint are shown to have the possibility of running simultaneously. In general, the explicit representation of context conditions is ....

U. Montanari and F. Rossi. True concurrency in concurrent constraint programming. In Proc. ILPS91. MIT Press, 1991.

....results on the investigation of efficient compile time techniques for Constraint Logic and Concurrent Constraint Programming. These techniques are viewed as source to source program transformations between the two programming paradigms and are based on a concurrent semantics of CC programs [MR91]. Previous work [BH92] showed that it is possible to perform program transformations from Prolog to AKL 1 [JH91] allowing the latter to fully exploit the Independent And Parallelism (IAP) HR93] present in Prolog programs. When extending the transformation techniques to the CLP paradigm [JL87, ....

....has to be extended [GHM93] Second, compile time tools based on the extended notions have to be developed in order to capture the independence of goals, allowing such transformation. For this purpose an analysis of the programs turns out to be needed. Our analysis will be based on a semantics [MR91] which, although originally intended for CC programming, can be also applied to CLP, if suitably extended [BGHMR94] Such semantics allows us to capture the dependencies present in a CLP program at a finer level of granularity than ever proposed to date in the literature. This provides the ....

[Article contains additional citation context not shown here]

U. Montanari and F. Rossi. True-concurrency in Concurrent Constraint Programming. In V. Saraswat and K. Ueda, editors, Proceedings of the 1991 International Symposium on Logic Programming, pages 694--716, San Diego, USA, 1991. The MIT Press.

No context found.

U. Montanari and F. Rossi. True-concurrency in Concurrent Constraint Programming. In V. Saraswat and K. Ueda, editors, Proceedings of the 1991 International Symposium on Logic Programming, pages 694--716, San Diego, USA, 1991. The MIT Press.

No context found.

Montanari, U. and Rossi, F., True-Concurrency in Concurrent Constraint Programming, in V. Saraswat and K. Ueda, Eds., Proc. International Logic Programming Symposium '91, MIT Press, pp. 694-713.

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