10 research outputs found

    Defective Coloring on Classes of Perfect Graphs

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    In Defective Coloring we are given a graph GG and two integers χd\chi_d, Δ∗\Delta^* and are asked if we can χd\chi_d-color GG so that the maximum degree induced by any color class is at most Δ∗\Delta^*. We show that this natural generalization of Coloring is much harder on several basic graph classes. In particular, we show that it is NP-hard on split graphs, even when one of the two parameters χd\chi_d, Δ∗\Delta^* is set to the smallest possible fixed value that does not trivialize the problem (χd=2\chi_d = 2 or Δ∗=1\Delta^* = 1). Together with a simple treewidth-based DP algorithm this completely determines the complexity of the problem also on chordal graphs. We then consider the case of cographs and show that, somewhat surprisingly, Defective Coloring turns out to be one of the few natural problems which are NP-hard on this class. We complement this negative result by showing that Defective Coloring is in P for cographs if either χd\chi_d or Δ∗\Delta^* is fixed; that it is in P for trivially perfect graphs; and that it admits a sub-exponential time algorithm for cographs when both χd\chi_d and Δ∗\Delta^* are unbounded

    35th Symposium on Theoretical Aspects of Computer Science: STACS 2018, February 28-March 3, 2018, Caen, France

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