Involution factorizations of Ewens random permutations

Fuente: arXiv
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Main Author: Burnette, Charles
Format: Preprint
Published: 2021
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author Burnette, Charles
author_facet Burnette, Charles
contents An involution is a bijection that is its own inverse. Given a permutation $σ$ of $[n],$ let $\mathsf{invol}(σ)$ denote the number of ways $σ$ can be expressed as a composition of two involutions of $[n].$ We prove that the statistic $\mathsf{invol}$ is asymptotically lognormal when the symmetric groups $\mathfrak{S}_n$ are each equipped with Ewens Sampling Formula probability measures of some fixed positive parameter $θ.$ This paper strengthens and generalizes previously determined results about the limiting distribution of $\log(\mathsf{invol})$ for uniform random permutations, i.e. the specific case of $θ= 1$. We also investigate the first two moments of $\mathsf{invol}$ itself, detailing the phase transition in asymptotic behavior at $θ= 1,$ and provide a functional refinement and a convergence rate for the Gaussian limit law which is demonstrably optimal when $θ= 1.$
format Preprint
id arxiv_https___arxiv_org_abs_2105_12695
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Involution factorizations of Ewens random permutations
Burnette, Charles
Combinatorics
Probability
05A05, 05A16, 60C05
An involution is a bijection that is its own inverse. Given a permutation $σ$ of $[n],$ let $\mathsf{invol}(σ)$ denote the number of ways $σ$ can be expressed as a composition of two involutions of $[n].$ We prove that the statistic $\mathsf{invol}$ is asymptotically lognormal when the symmetric groups $\mathfrak{S}_n$ are each equipped with Ewens Sampling Formula probability measures of some fixed positive parameter $θ.$ This paper strengthens and generalizes previously determined results about the limiting distribution of $\log(\mathsf{invol})$ for uniform random permutations, i.e. the specific case of $θ= 1$. We also investigate the first two moments of $\mathsf{invol}$ itself, detailing the phase transition in asymptotic behavior at $θ= 1,$ and provide a functional refinement and a convergence rate for the Gaussian limit law which is demonstrably optimal when $θ= 1.$
title Involution factorizations of Ewens random permutations
topic Combinatorics
Probability
05A05, 05A16, 60C05
url https://arxiv.org/abs/2105.12695