Log-concavity of longest increasing subsequence

Yupeng Li

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arXiv · 2610.36483

Log-concavity of longest increasing subsequence

Yupeng Li

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Abstract

We prove a conjecture proposed by Chen that, for every fixed $n$, the sequence $(a_{n,k})_{k=1}^n$ is log-concave, where $a_{n,k}$ counts permutations of $[n]$ whose longest increasing subsequence has length $k$.

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Yupeng Li. 2026-10-27. Log-concavity of longest increasing subsequence. https://arxiv.org/abs/2610.36483

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