Author(s)

P. Baptiste, B. Legeard, M.A. Manier & C. Varnier

Abstract

Optimization with constraint logic programming: the hoist scheduling problem solved with various solvers P. Baptiste, B. Legeard, M.-A. Manier & C. Varnier Laboratoire d'Automatique de Besangon, Impasse 25000 BE^TVCCW, France ABSTRACT The Hoist Scheduling Problem in electroplating facilities is known as an NP-Hard and strongly constrained problem. Up to now, the Operational Research approach appeared to be limited to the resolution of specific kinds of lines. We have proposed a new approach using the Constraint Logic Programming. In this paper we give a model for simple lines, aiming at providing the optimal solution for the 1-periodic problem, and that can easily be extended. Then we compare the performances of two kinds of solvers: PROLOG in that uses rational variables, and CHIP that uses finite domains. We finally give results for a benchmark example. INTRODUCTION The Hoist Scheduling Problem deals with scheduling the movements of hoists in most ele

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