List coloring in the absence of a linear forest

  • Authors:
  • Petr A. Golovach;Daniël Paulusma

  • Affiliations:
  • School of Engineering and Computing Sciences, Durham University, Science Laboratories, Durham, United Kingdom;School of Engineering and Computing Sciences, Durham University, Science Laboratories, Durham, United Kingdom

  • Venue:
  • WG'11 Proceedings of the 37th international conference on Graph-Theoretic Concepts in Computer Science
  • Year:
  • 2011

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Abstract

The k-Coloring problem is to decide whether a graph can be colored with at most k colors such that no two adjacent vertices receive the same color. The Listk-Coloring problem requires in addition that every vertex u must receive a color from some given set L(u)⊆{1,…,k}. Let Pn denote the path on n vertices, and G+H and rH the disjoint union of two graphs G and H and r copies of H, respectively. For any two fixed integers k and r, we show that Listk-Coloring can be solved in polynomial time for graphs with no induced rP1+P5, hereby extending the result of Hoàng, Kami$#324;ski, Lozin, Sawada and Shu for graphs with no induced P5. Our result is tight; we prove that for any graph H that is a supergraph of P1+P5 with at least 5 edges, already List 5-Coloring is NP-complete for graphs with no induced H. We also show that Listk-Coloring is fixed parameter tractable in k+r on graphs with no induced rP1+P2, and that k-Coloring restricted to such graphs allows a polynomial kernel when parameterized by k. Finally, we show that Listk-Coloring is fixed parameter tractable in k for graphs with no induced P1+P3.