An almost complete $t$-intersection theorem for permutations

Andrey Kupavskii

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arXiv · 2405.07843

An almost complete $t$-intersection theorem for permutations

Andrey Kupavskii

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Abstract

For any $\epsilon>0$ and $n>(1+\epsilon)t$, $n>n_0(\epsilon)$ we determine the size of the largest $t$-intersecting family of permutations, as well as give a sharp stability result. This resolves a conjecture of Ellis, Friedgut and Pilpel (2011) and shows the validity of conjectures of Frankl and Deza (1977) and Cameron (1988) for $n>(1+\epsilon )t$. We note that, for this range of parameters, the extremal examples are not necessarily trivial, and that our statement is analogous to the celebrated Ahlswede-Khachatrian theorem. The proof is based on the refinement of the method of spread approximations, recently introduced by Kupavskii and Zakharov (2022).

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Andrey Kupavskii. 2024-05-13. An almost complete $t$-intersection theorem for permutations. https://arxiv.org/abs/2405.07843

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