On the effectiveness of the linear programming relaxation of the 0-1 multi-commodity minimum cost network flow problem

  • Authors:
  • Dae-Sik Choi;In-Chan Choi

  • Affiliations:
  • Department of Industrial Systems and Information Engineering, Korea University, Seoul, South Korea;Department of Industrial Systems and Information Engineering, Korea University, Seoul, South Korea

  • Venue:
  • COCOON'06 Proceedings of the 12th annual international conference on Computing and Combinatorics
  • Year:
  • 2006

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Abstract

Several studies have reported that the linear program relaxation of integer multi-commodity network flow problems often provides integer optimal solutions. We explore this phenomenon with a 0-1 multi-commodity network with mutual arc capacity constraints. Characteristics of basic solutions in the linear programming relaxation problem of the 0-1 multi-commodity problem are identified. Specifically, necessary conditions for a linear programming relaxation to have a non-integer solution are presented. Based on the observed characteristics, a simple illustrative example problem is constructed to show that its LP relaxation problem has integer optimal solutions with a relatively high probability. Furthermore, to investigate whether or not and under what conditions this tendency applies to large-sized problems, we have carried out computational experiments by using randomly generated problem instances. The results of our computational experiment indicate that there exists a narrow band of arc density in which the 0-1 multi-commodity problems possess no integer optimal solutions.