题目：A note on chromatic number and induced odd cycles

摘要：

We show that if a graph $G$ has neither triangles nor quadrilaterals, and has no odd holes of length

at least 7, then $/chi(G)/le 4$ and $/chi(G)/le 3$ if $G$ has radius at most $3$, and for each vertex

$u$ of $G$, the set of vertices of the same distance to $u$ induces a bipartite subgraph.

This  answers some questions of Plummer and Zha.  Joint work with Gexin Yu and Xiaoya Zha.

欢迎感兴趣的师生前来参加！