Claw-free graphs VI. Colouring

In this paper we prove that if G is a connected claw-free graph with three pairwise non-adjacent vertices, with chromatic number x and clique number omega, then x <= 2 omega and the same for the complement of G. We also prove that the choice number of G is at most 2 omega. except possibly in the case when G can be obtained from a subgraph of the Schlafli graph by replicating vertices. Finally, we show that the constant 2 is best possible in all cases. (C) 2010 Elsevier Inc. All rights reserved.