Locating Sources to Meet Flow Demands in Undirected Networks

  • Authors:
  • Kouji Arata;Satoru Iwata;Kazuhisa Makino;Satoru Fujishige

  • Affiliations:
  • -;-;-;-

  • Venue:
  • SWAT '00 Proceedings of the 7th Scandinavian Workshop on Algorithm Theory
  • Year:
  • 2000

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Abstract

This paper deals with the problem of finding a minimum-cost vertex subset S in an undirected network such that for each vertex v we can send d(v) units of flow from S to v. Although this problem is NP-hard in general, Tamura et al. have presented a greedy algorithm for solving the special case with uniform costs on the vertices. We give a simpler proof on the validity of the greedy algorithm using linear programming duality and improve the running time bound from O(n2M) to O(nM), where n is the number of vertices in the network and M denotes the time for max-flow computation in the network with n vertices and m edges. We also present an O(n(m+n log n)) time algorithm for the special case with uniform demands and arbitrary costs.