Parameterized Algorithms and Hardness Results for Some Graph Motif Problems

  • Nadja Betzler
  • Michael R. Fellows
  • Christian Komusiewicz
  • Rolf Niedermeier
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5029)

Abstract

We study the NP-complete Graph Motif problem: given a vertex-colored graph G = (V,E) and a multiset M of colors, does there exist an S ⊆ V such that G[S] is connected and carries exactly (also with respect to multiplicity) the colors in M? We present an improved randomized algorithm for Graph Motif with running time O(4.32|M|·|M|2·|E|). We extend our algorithm to list-colored graph vertices and the case where the motif G[S] needs not be connected. By way of contrast, we show that extending the request for motif connectedness to the somewhat “more robust” motif demands of biconnectedness or bridge-connectedness leads to W[1]-complete problems. Actually, we show that the presumably simpler problems of finding (uncolored) biconnected or bridge-connected subgraphs are W[1]-complete with respect to the subgraph size. Answering an open question from the literature, we further show that the parameter “number of connected motif components” leads to W[1]-hardness even when restricted to graphs that are paths.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2008

Authors and Affiliations

  • Nadja Betzler
    • 1
  • Michael R. Fellows
    • 2
  • Christian Komusiewicz
    • 1
  • Rolf Niedermeier
    • 1
  1. 1.Institut für InformatikFriedrich-Schiller-Universität JenaJenaGermany
  2. 2.PC Research Unit, Office of DVC (Research)University of NewcastleCallaghanAustralia

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