On Efficient Fixed Parameter Algorithms for WEIGHTED VERTEX COVER

  • Authors:
  • Rolf Niedermeier;Peter Rossmanith

  • Affiliations:
  • -;-

  • Venue:
  • ISAAC '00 Proceedings of the 11th International Conference on Algorithms and Computation
  • Year:
  • 2000

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Abstract

We investigate the fixed parameter complexity of one of the most popular problems in combinatorial optimization, WEIGHTED VERTEX COVER. Given a graph G = (V, E), a weight function ω: V → R+, and k ∈ R+, WEIGHETD VERTEX COVER (WVC for short) asks for a subset C of vertices in V of weight at most k such that every edge of G has at least one endpoint in C. WVC and its variants have all been shown to be NP-complete. We show that, when restricting the range of ω to positive integers, the so-called INTEGER-WVC can be solved as fast as unweighted VERTEX COVER. Our main result is that if the range of ω is restricted to positive reals ≥ 1, then so-called REAL-WVC can be solved in time O(1.3954k + k|V|). If we modify the problem in such a way that k is not the weight of the vertex cover we are looking for, but the number of vertices in a minimum weight vertex cover, then the same running time can be obtained. If the weights are arbitrary (referred to by GENERAL-WVC), however, the problem is not fixed parameter tractable unless P = NP.