Substitutes and complements in network flows viewed as discrete convexity

  • Authors:
  • Kazuo Murota;Akiyoshi Shioura

  • Affiliations:
  • Graduate School of Information Science and Technology, University of Tokyo, Tokyo 113-8656, Japan and PRESTO, JST, Japan;Graduate School of Information Sciences, Tohoku University, Sendai 980-8579, Japan

  • Venue:
  • Discrete Optimization
  • Year:
  • 2005

Quantified Score

Hi-index 0.00

Visualization

Abstract

We study combinatorial properties of the optimal value function of the network flow problem. It is shown by Gale-Politof [Substitutes and complements in networks flow problems, Discrete Appl. Math. 3 (1981) 175-186] that the optimal value function has submodularity and supermodularity w.r.t. problem parameters such as weights and capacities. In this paper we shed a new light on this result from the viewpoint of discrete convex analysis to point out that the submodularity and supermodularity are naturally implied by discrete convexity, called M-convexity and L-convexity, of the optimal value function.