Clustering with Partial Information

  • Authors:
  • Hans L. Bodlaender;Michael R. Fellows;Pinar Heggernes;Federico Mancini;Charis Papadopoulos;Frances Rosamond

  • Affiliations:
  • Department of Information and Computing Sciences, Utrecht University, The Netherlands;PCRU, Office of DVC (Research), University of Newcastle, Australia;Department of Informatics, University of Bergen, Bergen, Norway N-5020;Department of Informatics, University of Bergen, Bergen, Norway N-5020;Department of Informatics, University of Bergen, Bergen, Norway N-5020;PCRU, Office of DVC (Research), University of Newcastle, Australia

  • Venue:
  • MFCS '08 Proceedings of the 33rd international symposium on Mathematical Foundations of Computer Science
  • Year:
  • 2008

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Abstract

The Correlation Clusteringproblem, also known as the Cluster Editingproblem, seeks to edit a given graph by adding and deleting edges to obtain a collection of vertex-disjoint cliques, such that the editing cost is minimized. The Edge Clique Partitioningproblem seeks to partition the edges of a given graph into edge-disjoint cliques, such that the number of cliques is minimized. Both problems are known to be NP-hard, and they have been previously studied with respect to approximation and fixed parameter tractability. In this paper we study these two problems in a more general setting that we term fuzzy graphs, where the input graphs may have missing information, meaning that whether or not there is an edge between some pairs of vertices of the input graph can be undecided.For fuzzy graphs the Correlation Clusteringand Edge Clique Partitioningproblems have previously been studied only with respect to approximation. Here we give parameterized algorithms based on kernelization for both problems. We prove that the Correlation Clusteringproblem is fixed-parameter tractable on fuzzy graphs when parameterized by (k,r), where kis the editing cost and ris the minimum number of vertices required to cover the undecided edges. In particular we show that it has a polynomial-time reduction to a problem kernel on O(k2+ r) vertices. We provide an analogous result for the Edge Clique Partitioningproblem on fuzzy graphs. Using (k,r) as parameters, where kbounds the size of the partition, and ris the minimum number of vertices required to cover the undecided edges, we describe a polynomial-time kernelization to a problem kernel on O(k4·3r) vertices. This implies fixed-parameter tractability for this parameterization. Furthermore we also show that parameterizing only by the number of cliques k, is not enough to obtain fixed-parameter tractability. The problem remains, in fact, NP-hard for each fixed k 2.