Even-hole-free graphs still have bisimplicial vertices

Maria Chudnovsky; Paul Seymour

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arXiv · 1909.10967

Even-hole-free graphs still have bisimplicial vertices

Maria Chudnovsky·Paul Seymour

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Abstract

A {\em hole} in a graph is an induced subgraph which is a cycle of length at least four. A hole is called {\em even} if it has an even number of vertices. An {\em even-hole-free} graph is a graph with no even holes. A vertex of a graph is {\em bisimplicial} if the set of its neighbours is the union of two cliques. In an earlier paper \cite{bisimplicial}, Addario-Berry, Havet and Reed, with the authors, claimed to prove a conjecture of Reed, that every even-hole-free graph has a bisimplicial vertex, but we have recently been shown that the "proof" has a serious error. Here we give a proof using a different method.

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Maria Chudnovsky, Paul Seymour. 2020-05-15. Even-hole-free graphs still have bisimplicial vertices. https://arxiv.org/abs/1909.10967

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