Aldous-type Spectral Gaps in Unitary Groups

Fuente: arXiv
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Main Authors: Alon, Gil, Puder, Doron
Format: Preprint
Published: 2026
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_version_ 1866917300567801856
author Alon, Gil
Puder, Doron
author_facet Alon, Gil
Puder, Doron
contents Aldous' spectral gap conjecture, proven by Caputo, Liggett and Richthammer, states the following: for any set of transpositions in the symmetric group $\mathrm{Sym}(n)$, the spectral gap of the corresponding random walk on the group -- an $n!$-state process -- coincides with that of the corresponding random walk of a single element -- an $n$-state process. This paper presents an analog of this conjecture in the unitary group $\mathrm{U}(n)$, and proves it in several non-trivial cases. The phenomenon we discover is that for some natural families of probability distributions on $\mathrm{U}(n)$, the spectral gap of the corresponding random walk, which has a continuous state space, is identical to that of a discrete KMP process (also known as the uniform reshuffling process) with two indistinguishable particles on a hypergraph on $n$ vertices -- a discrete Markov chain with $\binom{n+1}{2}$ states.
format Preprint
id arxiv_https___arxiv_org_abs_2603_00353
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Aldous-type Spectral Gaps in Unitary Groups
Alon, Gil
Puder, Doron
Probability
Mathematical Physics
Combinatorics
Group Theory
20c15, 60K35 (Primary) 60B15, 60B20, 60J27, 05c50, 22c05, 05c81, 05c65 (Secondary)
Aldous' spectral gap conjecture, proven by Caputo, Liggett and Richthammer, states the following: for any set of transpositions in the symmetric group $\mathrm{Sym}(n)$, the spectral gap of the corresponding random walk on the group -- an $n!$-state process -- coincides with that of the corresponding random walk of a single element -- an $n$-state process. This paper presents an analog of this conjecture in the unitary group $\mathrm{U}(n)$, and proves it in several non-trivial cases. The phenomenon we discover is that for some natural families of probability distributions on $\mathrm{U}(n)$, the spectral gap of the corresponding random walk, which has a continuous state space, is identical to that of a discrete KMP process (also known as the uniform reshuffling process) with two indistinguishable particles on a hypergraph on $n$ vertices -- a discrete Markov chain with $\binom{n+1}{2}$ states.
title Aldous-type Spectral Gaps in Unitary Groups
topic Probability
Mathematical Physics
Combinatorics
Group Theory
20c15, 60K35 (Primary) 60B15, 60B20, 60J27, 05c50, 22c05, 05c81, 05c65 (Secondary)
url https://arxiv.org/abs/2603.00353