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arXiv · 2110.12710

On the chromatic number of a family of odd hole free graphs

Jialei Song·Baogang Xu
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Abstract

A hole is an induced cycle of length at least 4, and an odd hole is a hole of odd length. A full house is a graph composed by a vertex adjacent to both ends of an edge in $K_4$ . Let $H$ be the complement of a cycle on 7 vertices. Chudnovsky et al [6] proved that every (odd hole, $K_4$)-free graph is 4-colorable and is 3-colorable if it does not has $H$ as an induced subgraph. In this paper, we use the proving technique of Chudnovsky et al to generalize this conclusion to (odd hole, full house)-free graphs, and prove that for (odd hole, full house)-free graph $G$, $χ(G)\le ω(G)+1$, and the equality holds if and only if $ω(G)=3$ and $G$ has $H$ as an induced subgraph.

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Jialei Song, Baogang Xu. 2021-10-25. On the chromatic number of a family of odd hole free graphs. https://arxiv.org/abs/2110.12710

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