On Gelfand pairs and degenerate Gelfand-Graev modules of General Linear groups of degree two over principal ideal local rings of finite length

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Main Authors: Gupta, Archita, Singla, Pooja
Format: Preprint
Published: 2024
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author Gupta, Archita
Singla, Pooja
author_facet Gupta, Archita
Singla, Pooja
contents Let $R$ be a principal ideal local ring of finite length with a finite residue field of odd characteristic. Denote by $G(R)$ the general linear group of degree two over $R$, and by $B(R)$ the Borel subgroup of $G(R)$ consisting of upper triangular matrices. In this article, we prove that the pair $(G(R), B(R))$ is a strong Gelfand pair. We also investigate the decomposition of the degenerate Gelfand-Graev (DGG) modules of $G(R)$. It is known that the non-degenerate Gelfand Graev module (also called non-degenerate Whittaker model) of $G(R)$ is multiplicity-free. We characterize the DGG-modules where the multiplicities are independent of the cardinality of the residue field. We provide a complete decomposition of all DGG modules of $G(R)$ for $R$ of length at most four.
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id arxiv_https___arxiv_org_abs_2410_21761
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On Gelfand pairs and degenerate Gelfand-Graev modules of General Linear groups of degree two over principal ideal local rings of finite length
Gupta, Archita
Singla, Pooja
Representation Theory
Primary 20G05, Secondary 20C15, 20G25, 15B33
Let $R$ be a principal ideal local ring of finite length with a finite residue field of odd characteristic. Denote by $G(R)$ the general linear group of degree two over $R$, and by $B(R)$ the Borel subgroup of $G(R)$ consisting of upper triangular matrices. In this article, we prove that the pair $(G(R), B(R))$ is a strong Gelfand pair. We also investigate the decomposition of the degenerate Gelfand-Graev (DGG) modules of $G(R)$. It is known that the non-degenerate Gelfand Graev module (also called non-degenerate Whittaker model) of $G(R)$ is multiplicity-free. We characterize the DGG-modules where the multiplicities are independent of the cardinality of the residue field. We provide a complete decomposition of all DGG modules of $G(R)$ for $R$ of length at most four.
title On Gelfand pairs and degenerate Gelfand-Graev modules of General Linear groups of degree two over principal ideal local rings of finite length
topic Representation Theory
Primary 20G05, Secondary 20C15, 20G25, 15B33
url https://arxiv.org/abs/2410.21761