The internal Steiner tree problem: Hardness and approximations

  • Authors:
  • Chao-Wen Huang;Chia-Wei Lee;Huang-Ming Gao;Sun-Yuan Hsieh

  • Affiliations:
  • -;-;-;-

  • Venue:
  • Journal of Complexity
  • Year:
  • 2013

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Abstract

Given a graph G=(V,E) with a cost function c:E-R^+ and a vertex subset R@?V, an internal Steiner tree is a Steiner tree that contains all the vertices in R, and such that each vertex in R must be an internal vertex. The internal Steiner tree problem involves finding an internal Steiner tree T whose total cost @?"("u","v")"@?"E"("T")c(u,v) is the minimum. In this paper, we first show that the internal Steiner tree problem is MAX SNP-hard. We then present a (2@r+1)-approximation algorithm for solving the problem on complete graphs, where @r is an approximation ratio for the Steiner tree problem. Currently, the best-known @r is ln4+@e