On the complexity of the multicut problem in bounded tree-width graphs and digraphs

  • Authors:
  • Cédric Bentz

  • Affiliations:
  • LRI, University of Paris-Sud and CNRS, Orsay F-91405, France

  • Venue:
  • Discrete Applied Mathematics
  • Year:
  • 2008

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Abstract

Given an edge- or vertex-weighted graph or digraph and a list of source-sink pairs, the minimum multicut problem consists in selecting a minimum weight set of edges or vertices whose removal leaves no path from each source to the corresponding sink. This is a classical NP-hard problem, and we show that the edge version becomes tractable in bounded tree-width graphs if the number of source-sink pairs is fixed, but remains NP-hard in directed acyclic graphs and APX-hard in bounded tree-width and bounded degree unweighted digraphs. The vertex version, although tractable in trees, is proved to be NP-hard in unweighted cacti of bounded degree and bounded path-width.