Faster Fixed Parameter Tractable Algorithms for Undirected Feedback Vertex Set

  • Authors:
  • Venkatesh Raman;Saket Saurabh;C. R. Subramanian

  • Affiliations:
  • -;-;-

  • Venue:
  • ISAAC '02 Proceedings of the 13th International Symposium on Algorithms and Computation
  • Year:
  • 2002

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Abstract

We give a O(max{12k, (4 lg k)k} 驴 n驴) algorithm for testing whether an undirected graph on n vertices has a feedback vertex set of size at most k where O(n驴) is the complexity of the best matrix multiplication algorithm. The previous best fixed parameter tractable algorithm for the problem took O((2k + 1)k n2) time. The main technical lemma we prove and use to develop our algorithm is that that there exists a constant c such that, if an undirected graph on n vertices with minimum degree 3 has a feedback vertex set of size at most c驴n, then the graph will have a cycle of length at most 12. This lemma may be of independent interest.We also show that the feedback vertex set problem can be solved in O(dk kn) for some constant d in regular graphs, almost regular graphs and (fixed) bounded degree graphs.