A necessary and sufficient condition for double coset lumping of Markov chains on groups with an application to the random to top shuffle

Fuente: arXiv
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Autori principali: Britnell, John R., Wildon, Mark
Natura: Preprint
Pubblicazione: 2023
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author Britnell, John R.
Wildon, Mark
author_facet Britnell, John R.
Wildon, Mark
contents Let $Q$ be a probability measure on a finite group $G$, and let $H$ be a subgroup of $G$. We show that a necessary and sufficient condition for the random walk driven by $Q$ on $G$ to induce a Markov chain on the double coset space $H\backslash G/H$, is that $Q(gH)$ is constant as $g$ ranges over any double coset of $H$ in $G$. We obtain this result as a corollary of a more general theorem on the double cosets $H \backslash G / K$ for $K$ an arbitrary subgroup of $G$. As an application we study a variation on the $r$-top to random shuffle which we show induces an irreducible, recurrent, reversible and ergodic Markov chain on the relevant double cosets. The transition matrix of the induced walk has remarkable spectral properties: we find its invariant distribution and its eigenvalues and hence determine its rate of convergence.
format Preprint
id arxiv_https___arxiv_org_abs_2311_02723
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle A necessary and sufficient condition for double coset lumping of Markov chains on groups with an application to the random to top shuffle
Britnell, John R.
Wildon, Mark
Group Theory
Combinatorics
Probability
20A05 (Primary), 15A18, 15B51, 60G10, 60J10 (Secondary)
Let $Q$ be a probability measure on a finite group $G$, and let $H$ be a subgroup of $G$. We show that a necessary and sufficient condition for the random walk driven by $Q$ on $G$ to induce a Markov chain on the double coset space $H\backslash G/H$, is that $Q(gH)$ is constant as $g$ ranges over any double coset of $H$ in $G$. We obtain this result as a corollary of a more general theorem on the double cosets $H \backslash G / K$ for $K$ an arbitrary subgroup of $G$. As an application we study a variation on the $r$-top to random shuffle which we show induces an irreducible, recurrent, reversible and ergodic Markov chain on the relevant double cosets. The transition matrix of the induced walk has remarkable spectral properties: we find its invariant distribution and its eigenvalues and hence determine its rate of convergence.
title A necessary and sufficient condition for double coset lumping of Markov chains on groups with an application to the random to top shuffle
topic Group Theory
Combinatorics
Probability
20A05 (Primary), 15A18, 15B51, 60G10, 60J10 (Secondary)
url https://arxiv.org/abs/2311.02723