A golden ratio parameterized algorithm for cluster editing

  • Authors:
  • Sebastian Böcker

  • Affiliations:
  • Lehrstuhl für Bioinformatik, Friedrich-Schiller-Universität Jena, Jena, Germany

  • Venue:
  • IWOCA'11 Proceedings of the 22nd international conference on Combinatorial Algorithms
  • Year:
  • 2011

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Abstract

The Cluster Editing problem asks to transform a graph by at most k edge modifications into a disjoint union of cliques. The problem is NP-complete, but several parameterized algorithms are known. We present a novel search tree algorithm for the problem, which improves running time from O*(1.76k) to O*(1.62k). In detail, we can show that we can always branch with branching vector (2,1) or better, resulting in the golden ratio as the base of the search tree size. Our algorithm uses a well-known transformation to the integer-weighted counterpart of the problem. To achieve our result, we combine three techniques: First, we show that zero-edges in the graph enforce structural features that allow us to branch more efficiently. Second, by repeatedly branching we can isolate vertices, releasing costs. Finally, we use a known characterization of graphs with few conflicts.