Split Vertex Deletion meets Vertex Cover: New fixed-parameter and exact exponential-time algorithms

  • Authors:
  • Marek Cygan;Marcin Pilipczuk

  • Affiliations:
  • IDSIA, University of Lugano, Switzerland;Institute of Informatics, University of Warsaw, Poland

  • Venue:
  • Information Processing Letters
  • Year:
  • 2013

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Abstract

In the Split Vertex Deletion problem, given a graph G and an integer k, we ask whether one can delete k vertices from the graph G to obtain a split graph (i.e., a graph, whose vertex set can be partitioned into two sets: one inducing a clique and the second one inducing an independent set). In this paper we study exact (exponential-time) and fixed-parameter algorithms for Split Vertex Deletion.*We show that, up to a factor quasipolynomial in k and polynomial in n, the Split Vertex Deletion problem can be solved in the same time as the well-studied Vertex Cover problem. By plugging in the currently best fixed-parameter algorithm for Vertex Cover due to Chen et al. [Theor. Comput. Sci. 411 (40-42) (2010) 3736-3756], we obtain an algorithm that solves Split Vertex Deletion in time O(1.2738^kk^O^(^l^o^g^k^)+n^3). *We show that all maximal induced split subgraphs of a given n-vertex graph can be listed in O(3^n^/^3n^O^(^l^o^g^n^)) time. To achieve our goals, we prove the following structural result that may be of independent interest: for any graph G we may compute a family P of size n^O^(^l^o^g^n^) containing partitions of V(G) into two parts, such that for any two disjoint sets X"C,X"I@?V(G) where G[X"C] is a clique and G[X"I] is an independent set, there is a partition in P which contains all vertices of X"C on one side and all vertices of X"I on the other. Moreover, the family P can be enumerated in O(n^O^(^l^o^g^n^)) time.