The class of 2K2-free graphs and its various subclasses have been studied in a variety of contexts. In this paper, we are concerned with the colouring of (P3 ∪ P2)- free graphs, a super class of 2K2-free graphs. We derive a O(ω3) upper bound for the chromatic number of(P3∪P2)-free graphs, and sharper bounds for(P3∪P2, diamond) free graphs and for (2K2, diamond)-free graphs, where ω denotes the clique number The last two classes are perfect if ω ≥ 5 and ≥ 4 respectively.

EB00000003425K

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