Homogeneous spaces of semidirect products and finite Gelfand pairs

Fuente: arXiv
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Autores principales: Ceccherini-Silberstein, Tullio, Scarabotti, Fabio, Tolli, Filippo
Formato: Preprint
Publicado: 2024
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author Ceccherini-Silberstein, Tullio
Scarabotti, Fabio
Tolli, Filippo
author_facet Ceccherini-Silberstein, Tullio
Scarabotti, Fabio
Tolli, Filippo
contents Let $K\leq H$ be two finite groups and let $C\leq A$ be two finite abelian groups, with $H$ acting on $A$ as a group of isomorphisms admitting $C$ as a $K$-invariant subgroup. We study the homogeneous space $X\coloneqq\left(H\ltimes A\right)/\left(K\ltimes C\right)$ and determine the decomposition of the permutation representation of $H\ltimes A$ acting on $X$. We then characterize when this is multiplicity-free, that is, when $\left(H\ltimes A,K\ltimes C\right)$ is a Gelfand pair. If this is the case, we explicitly calculate the corresponding spherical functions. From our general construction and related analysis, we recover Dunkl's results on the $q$-analog of the nonbinary Johnson scheme.
format Preprint
id arxiv_https___arxiv_org_abs_2405_08371
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Homogeneous spaces of semidirect products and finite Gelfand pairs
Ceccherini-Silberstein, Tullio
Scarabotti, Fabio
Tolli, Filippo
Representation Theory
Combinatorics
Functional Analysis
Group Theory
20C15, 20G40, 33C55, 43A90, 20E22
Let $K\leq H$ be two finite groups and let $C\leq A$ be two finite abelian groups, with $H$ acting on $A$ as a group of isomorphisms admitting $C$ as a $K$-invariant subgroup. We study the homogeneous space $X\coloneqq\left(H\ltimes A\right)/\left(K\ltimes C\right)$ and determine the decomposition of the permutation representation of $H\ltimes A$ acting on $X$. We then characterize when this is multiplicity-free, that is, when $\left(H\ltimes A,K\ltimes C\right)$ is a Gelfand pair. If this is the case, we explicitly calculate the corresponding spherical functions. From our general construction and related analysis, we recover Dunkl's results on the $q$-analog of the nonbinary Johnson scheme.
title Homogeneous spaces of semidirect products and finite Gelfand pairs
topic Representation Theory
Combinatorics
Functional Analysis
Group Theory
20C15, 20G40, 33C55, 43A90, 20E22
url https://arxiv.org/abs/2405.08371