Hitting time mixing for the random transposition walk

Fuente: arXiv
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Hauptverfasser: Jain, Vishesh, Sawhney, Mehtaab
Format: Preprint
Veröffentlicht: 2024
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author Jain, Vishesh
Sawhney, Mehtaab
author_facet Jain, Vishesh
Sawhney, Mehtaab
contents Consider shuffling a deck of $n$ cards, labeled $1$ through $n$, as follows: at each time step, pick one card uniformly with your right hand and another card, independently and uniformly with your left hand; then swap the cards. How long does it take until the deck is close to random? Diaconis and Shahshahani showed that this process undergoes cutoff in total variation distance at time $t = \lfloor n\log{n}/2 \rfloor$. Confirming a conjecture of N.~Berestycki, we prove the definitive ``hitting time'' version of this result: let $τ$ denote the first time at which all cards have been touched. The total variation distance between the stopped distribution at $τ$ and the uniform distribution on permutations is $o_n(1)$; this is best possible, since at time $τ-1$, the total variation distance is at least $(1+o_n(1))e^{-1}$.
format Preprint
id arxiv_https___arxiv_org_abs_2410_23944
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Hitting time mixing for the random transposition walk
Jain, Vishesh
Sawhney, Mehtaab
Probability
Consider shuffling a deck of $n$ cards, labeled $1$ through $n$, as follows: at each time step, pick one card uniformly with your right hand and another card, independently and uniformly with your left hand; then swap the cards. How long does it take until the deck is close to random? Diaconis and Shahshahani showed that this process undergoes cutoff in total variation distance at time $t = \lfloor n\log{n}/2 \rfloor$. Confirming a conjecture of N.~Berestycki, we prove the definitive ``hitting time'' version of this result: let $τ$ denote the first time at which all cards have been touched. The total variation distance between the stopped distribution at $τ$ and the uniform distribution on permutations is $o_n(1)$; this is best possible, since at time $τ-1$, the total variation distance is at least $(1+o_n(1))e^{-1}$.
title Hitting time mixing for the random transposition walk
topic Probability
url https://arxiv.org/abs/2410.23944