Computational Logic and Computational Methods

	Computational Logic and Computational Methods

	Funding: The project is funded by part by: Royal Society, U.K., Faculty of Informatics, Grant Agency of the Czech Republic
	Starting Date: January 1, 1995
	Coordinator: D. R. Gilbert (City University, U.K.)
	Project Leader at FI: L. Brim

Description	The Computational Logic and Computational Methods project aims at the research in the theory and applications of both computational logic, including constraint programming, as well as novel computational methods and models. Specific active research topics are: Concurrent and Distributed Systems: synchronous concurrent constraint programming (FI) semantics of interaction (CU) distributed concurrent constraint programming (CU) workbench for concurrent constraint programming languages (CU) real-time and distributed constraint systems (FI) formal semantics (CU) Probability and computation probabilistic methods in semantics (CU) novel computational methods in constraints (CU) Applications constraints and bioinformatics (CU) Over-constrained systems (CU)

Role of FI	Synchronous Concurrent Constraints (Scc) Concurrent constraint programming is classically based on asynchronous communication via a shared store. This is obtained by ask primitives blocking when the information on the store is not complete enough to entail the asked constraints. Following these lines, a natural way of obtaining synchronous communication in concurrent constraint programming is to force the reduction of ask and tell primitives to synchronise. Specifically, in our approach, a tell operation is reduced when an ask operation requires the told information. Moreover, the reduction of the two primitives is performed simultaneously. However, there is no reason to block ask and tell primitives on information which is already present. Consequently, any tell(c) and ask(c) operations whose constraint argument c is entailed by the current store are reduced without partners. The scheme is finally made slightly more general by, on the one hand, permitting the synchronisation of more than two partners and, on the other hand, introducing a fictitious tell primitive which leaves the store unchanged but allows for synchronisation. Contact: Lubos Brim, David Gilbert (City University London, U.K.), Jean-Marie Jacquet (University of Namur, Belgium) and Mojmir Kretinsky Real-time and distributed systems The focus is on the area of real-time and distributed systems, particularly within the computational logic paradigm. The goal is to extend known formalisms to deal with quantitative and distributed aspects of concurrent constraint systems. Recently, contacts with Philippe Codognet and co-workers from INRIA-Rocquencourt, France, based on joint interest in investigating extensions of the CC programming paradigm and in particular integrating an adequate notion of time in such concurrent languages, moving therefore towards a framework for real-time systems have been established. Contact: Lubos Brim

Cooperating Organisations	Faculty of Informatics, Masaryk University Brno City University London, U.K. University of Namur, Belgium

People	Mojmir Kretinsky David Gilbert (City University, U.K.), Alessandra Di Pierro (City University, U.K.), Herbert Wiklicky (City University, U.K.), Alexander Letichevsky (City University, U.K.), Lubos Brim, Jean-Marie Jacquet (University of Namur, Belgium)

Contact	Lubos Brim , M. Kretinsky

Publications	L. Brim, M. Kretinsky, D.R. Gilbert, J-M Jacquet: Temporal Synchronous Concurrent Constraint Programming , presented at COTIC 97 1st International Workshop on Constraint programming for time critical applications held in conjunction with the Third International Conference on Principles and Practice of Constraint Programming (CP97), October 29 - November 1, 1997. L. Brim, M. Kretinsky, D.R. Gilbert, J-M Jacquet: Temporal Synchronous Concurrent Constraint Programming , Technical Report No. 1997/06. ISSN 1364-4009, 15 pages. Full paper is available. L. Brim, D.R. Gilbert, J-M Jacquet, M. Kretinsky, A Process Algebra for Synchronous Concurrent Constraint Programming, Proceedings of ALP96: Fifth International Conference on Algebraic and Logic Programming, Michael Hanus and Mario Rodríguez-Artalejo (Editors), pp 165-178, Springer LNCS volume 1139, ISBN 3-540-61735-3, Aachen, Germany, September 24-27, 1996. L. Brim, J-M. Jacquet, D. Gilbert and M. Kretinsky: Synchronisation in Scc, in ILPS'95: Proceedings of the International Logic Programming Symposium, Ed John Lloyd, MIT Press, ISBN 0-262-62099-5, 1995. Alma Osmanovic, David Gilbert, Lubos Brim, Mojmir Kretinsky and Jean-Marie Jacquet An interpreter for Scc, presented at the Second workshop of the INTAS-93-1702 project Efficient Symbolic Computing St Petersburg, Russia, October 1996. Lubos Brim, David Gilbert and Mojmír Kretínský, Operational Semantics of Logical Concurrent Systems, Proceedings of the UK-ALP Workshop on Concurrency in Computational Logic, David Gilbert and Jean-Marie Jacquet (eds), December 1993 L. Brim, D.R. Gilbert, J-M Jacquet, M. Kretinsky: A Process Algebra for Synchronous Concurrent Constraint Programming , Technical Report No. 1996/06. ISSN 1364-4009, 15 pages. Full paper is available. L. Brim, D.R. Gilbert, J-M Jacquet, M. Kretinsky: New versions of ask and tell for synchronous communication in concurrent constraint programming , Technical Report No. 1996/03. ISSN 1364-4009, 18 pages. Full paper is available.

Other Information	The research group participates in the ERCIM Working Group on Constraints.



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Concurrent and Distributed Systems:

Probability and computation

Applications

Over-constrained systems (CU)

Synchronous Concurrent Constraints (Scc)

Real-time and distributed systems