Combining arc-consistency and dual lagrangean relaxation for filtering CSPs

  • Authors:
  • Mohand Ou Idir Khemmoudj;Hachemi Bennaceur;Anass Nagih

  • Affiliations:
  • LIPN-CNRS UMR, Villetaneuse, France;LIPN-CNRS UMR, Villetaneuse, France;LIPN-CNRS UMR, Villetaneuse, France

  • Venue:
  • CPAIOR'05 Proceedings of the Second international conference on Integration of AI and OR Techniques in Constraint Programming for Combinatorial Optimization Problems
  • Year:
  • 2005

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Abstract

This paper presents a CSPs filtering method combining arc-consistency and dual Lagrangean relaxation techniques. First, we model the constraint satisfaction problem as a 0/1 linear integer program (IP); then, the consistency of a value is defined as an optimization problem on which a dual Lagrangean relaxation is defined. While solving the dual Lagrangean relaxation, values inconsistencies may be detected (dual Lagrangean inconsistent values); the constraint propagation of this inconsistency can be performed by arc-consistency. After having made the CSP arc-consistent, the process iteratively selects values of variables which may be dual Lagrangean inconsistent. Computational experiments performed over randomly generated problems show the advantages of the hybrid filtering technique combining arc-consistency and dual Lagrangean relaxation.