Random partitions under the Plancherel-Hurwitz measure, high genus Hurwitz numbers and maps

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Autori principali: Chapuy, Guillaume, Louf, Baptiste, Walsh, Harriet
Natura: Preprint
Pubblicazione: 2022
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author Chapuy, Guillaume
Louf, Baptiste
Walsh, Harriet
author_facet Chapuy, Guillaume
Louf, Baptiste
Walsh, Harriet
contents We study the asymptotic behaviour of random integer partitions under a new probability law that we introduce, the Plancherel-Hurwitz measure. This distribution, which has a natural definition in terms of Young tableaux, is a deformation of the classical Plancherel measure which appears naturally in the context of Hurwitz numbers, enumerating certain transposition factorisations in symmetric groups. We study a regime in which the number of factors in the underlying factorisations grows linearly with the order of the group, and the corresponding topological objects, Hurwitz maps, are of high genus. We prove that the limiting behaviour exhibits a new, twofold, phenomenon: the first part becomes very large, while the rest of the partition has the standard Vershik-Kerov-Logan-Shepp limit shape. As a consequence, we obtain asymptotic estimates for unconnected Hurwitz numbers with linear Euler characteristic, which we use to study random Hurwitz maps in this regime. This result can also be interpreted as the return probability of the transposition random walk on the symmetric group after linearly many steps.
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id arxiv_https___arxiv_org_abs_2206_11315
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Random partitions under the Plancherel-Hurwitz measure, high genus Hurwitz numbers and maps
Chapuy, Guillaume
Louf, Baptiste
Walsh, Harriet
Combinatorics
Mathematical Physics
Probability
We study the asymptotic behaviour of random integer partitions under a new probability law that we introduce, the Plancherel-Hurwitz measure. This distribution, which has a natural definition in terms of Young tableaux, is a deformation of the classical Plancherel measure which appears naturally in the context of Hurwitz numbers, enumerating certain transposition factorisations in symmetric groups. We study a regime in which the number of factors in the underlying factorisations grows linearly with the order of the group, and the corresponding topological objects, Hurwitz maps, are of high genus. We prove that the limiting behaviour exhibits a new, twofold, phenomenon: the first part becomes very large, while the rest of the partition has the standard Vershik-Kerov-Logan-Shepp limit shape. As a consequence, we obtain asymptotic estimates for unconnected Hurwitz numbers with linear Euler characteristic, which we use to study random Hurwitz maps in this regime. This result can also be interpreted as the return probability of the transposition random walk on the symmetric group after linearly many steps.
title Random partitions under the Plancherel-Hurwitz measure, high genus Hurwitz numbers and maps
topic Combinatorics
Mathematical Physics
Probability
url https://arxiv.org/abs/2206.11315