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Departamento de Informática, Universidade Federal do Espírito Santo (UFES), Vitória, ES 29060-970, Brazil
The one-dimensional facility layout problem is concerned with arranging n departments of given lengths on a line, while minimizing the weighted sum of the distances between all pairs of departments. The problem is NP-hard because it is a generalization of the minimum linear arrangement problem. In this paper, a 0-1 quadratic programming model consisting of only O(n2) 0-1 variables is proposed for the problem. Subsequently, this model is cast as an equivalent mixed-integer program and then reduced by preprocessing. Next, additional redundant constraints are introduced and linearized in a higher space to achieve an equivalent mixed 0-1 linear program, whose continuous relaxation provides an approximation of the convex hull of solutions to the quadratic program. It is shown that the resulting mixed 0-1 linear program is more efficient than previously published mixed-integer formulations. In the computational results, several problem instances taken from the literature were efficiently solved to optimality. Moreover, it is now possible to efficiently solve problems of a larger size.
amaral{at}inf.ufes.br
Subject classifications: facilities/equipment planning; layout; programming; integer.
History: Received June 2005;
revision received May 2006;
accepted April 2007.
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