Conference Paper

# Making AC-3 an Optimal Algorithm.

Conference: Proceedings of the Seventeenth International Joint Conference on Artificial Intelligence, IJCAI 2001, Seattle, Washington, USA, August 4-10, 2001

Source: DBLP

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**ABSTRACT:**a b s t r a c t This paper concerns project scheduling under resource constraints. Traditionally, the objective is to find a unique solution that minimizes the project makespan, while respecting the precedence constraints and the resource constraints. This work focuses on developing a model and a decision support framework for industrial application of the cumulative global constraint. For a given project scheduling, the proposed approach allows the generation of different optimal solutions relative to the alternate availability of out-sourcing and resources. The objective is to provide a decision-maker an assistance to construct, choose, and define the appropriate scheduling program taking into account the possible capacity resources. The industrial problem under consideration is modeled as a constraint satisfaction problem (CSP). It is imple-mented under the constraint programming language CHIP V5. The provided solutions determine values for the various variables associated to the tasks realized on each resource, as well as the curves with the profile of the total consumption of resources on time.Computers & Industrial Engineering 09/2010; 61:357-363. · 1.69 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**RESUME : Cet article propose un modèle de planification d'une chaîne logistique, basé sur une structure décisionnelle à deux niveaux. Adoptant un processus dynamique permettant d'actualiser les données à chaque étape de planification, le premier niveau planifie la production en recherchant le meilleur compromis entre les leviers décisionnels disponibles liés aux aspects capacité et coût de production. Le deuxième niveau établit un ordonnancement des opérations de fabrication et de transport en minimisant la date de fin du planning. L'interaction entre les deux niveaux est établie par des contraintes de conservation d'énergie. Nous adoptons une approche par satisfaction de contraintes dynamiques («Dynamic Constraint Satisfaction Problem») permettant de mettre en évidence cette interaction. MOTS-CLES : Planification multi-site, approche multi-niveau, interaction énergétique, problèmes de satisfaction de contraintes dynamiques, robustesse, réactivité. -
##### Conference Paper: Reducing the Number of Useless Revisions Performed by Constraint Solvers Based on AC-3

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**ABSTRACT:**Maintaining arc-consistency during the search is one of the most widely used techniques in solving constraint satisfaction problems. Many algorithms have been developed in order to implement effectively arc-consistency, such as AC-3, AC-4, AC-6 or AC-7. While not as elaborate as others, AC-3 is simple to implement and proves to be efficient for many types of problems. In order to improve the overall performance of an AC-3 based solver it is essential to exploit any specific feature of the problem being solved. In this paper we describe a generic method to reduce the number of useless revisions performed by AC-3 based on the semantics of the constraints, as long as they provide custom information needed by our algorithm. Arithmetic constraints of the form ax + by ? c where x, y are variables of the constraint network, a,b,c are integer values and the operator ? ? {} fit naturally into this framework and AC3-OP becomes a particular case of our algorithm.2013 15th International Symposium on Symbolic and Numeric Algorithms for Scientific Computing (SYNASC); 09/2013

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