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arXiv · 2411.19173

Long induced paths in $K_{s, s}$-free graphs

Zach Hunter·Aleksa Milojević·Benny Sudakov·István Tomon
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Abstract

More than 40 years ago, Galvin, Rival and Sands showed that every $K_{s, s}$-free graph containing an $n$-vertex path must contain an induced path of length $f(n)$, where $f(n)\to \infty$ as $n\to \infty$. Recently, it was shown by Duron, Esperet and Raymond that one can take $f(n)=(\log \log n)^{1/5-o(1)}$. In this note, we give a short self-contained proof that a $K_{s, s}$-free graphs with an $n$-vertex path contains an induced path of length at least $(\log \log n)^{1-o(1)}$. Combined with the recent remarkable example of Couëtoux, Defrain, and Raymond, which provides an upper bound of $O((\log \log n)^{1+o(1)})$, this essentially resolves this old problem.

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Zach Hunter, Aleksa Milojević, Benny Sudakov, István Tomon. 2025-09-02. Long induced paths in $K_{s, s}$-free graphs. https://arxiv.org/abs/2411.19173

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