English

Universality of random permutations

Combinatorics 2020-05-27 v2

Abstract

It is a classical fact that for any ε>0\varepsilon > 0, a random permutation of length n=(1+ε)k2/4n = (1 + \varepsilon) k^2 / 4 typically contains a monotone subsequence of length kk. As a far-reaching generalization, Alon conjectured that a random permutation of this same length nn is typically kk-universal, meaning that it simultaneously contains every pattern of length kk. He also made the simple observation that for n=O(k2logk)n = O(k^2 \log k), a random length-nn permutation is typically kk-universal. We make the first significant progress towards Alon's conjecture by showing that n=2000k2loglogkn = 2000 k^2 \log \log k suffices.

Keywords

Cite

@article{arxiv.1911.12878,
  title  = {Universality of random permutations},
  author = {Xiaoyu He and Matthew Kwan},
  journal= {arXiv preprint arXiv:1911.12878},
  year   = {2020}
}
R2 v1 2026-06-23T12:30:30.504Z