On the extensions of certain representations of reductive algebraic groups with Frobenius maps

Fuente: arXiv
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Auteurs principaux: Chen, Xiaoyu, Dong, Junbin
Format: Preprint
Publié: 2024
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author Chen, Xiaoyu
Dong, Junbin
author_facet Chen, Xiaoyu
Dong, Junbin
contents Let ${\bf G}$ be a connected reductive algebraic group defined over the finite field $\mathbb{F}_q$ with $q$ elements,where $q$ is a power of a prime number $p$. Let $\Bbbk$ be a field and we study the extensions of certain $\bk\bg$-modules in this paper. We show that the extensions of any modules in $\mathscr{O}(\bg)$ by a finite-dimensional $\bk\bg$-module is zero if $p\ne \op{char}\bk\ge5$ or $\op{char}\bk=0$, where $\mathscr{O}(\bg)$ is the principal representation category defined in \cite{D1}. We determine the necessary and sufficient condition for the vanishing of extensions between naive induced modules. As an application, we give the condition of the vanishing of extensions between simple modules in $\mathscr{O}({\bf G})$ for $\bg=SL_2(\bar{\mathbb{F}}_q)$.
format Preprint
id arxiv_https___arxiv_org_abs_2404_09495
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the extensions of certain representations of reductive algebraic groups with Frobenius maps
Chen, Xiaoyu
Dong, Junbin
Representation Theory
Let ${\bf G}$ be a connected reductive algebraic group defined over the finite field $\mathbb{F}_q$ with $q$ elements,where $q$ is a power of a prime number $p$. Let $\Bbbk$ be a field and we study the extensions of certain $\bk\bg$-modules in this paper. We show that the extensions of any modules in $\mathscr{O}(\bg)$ by a finite-dimensional $\bk\bg$-module is zero if $p\ne \op{char}\bk\ge5$ or $\op{char}\bk=0$, where $\mathscr{O}(\bg)$ is the principal representation category defined in \cite{D1}. We determine the necessary and sufficient condition for the vanishing of extensions between naive induced modules. As an application, we give the condition of the vanishing of extensions between simple modules in $\mathscr{O}({\bf G})$ for $\bg=SL_2(\bar{\mathbb{F}}_q)$.
title On the extensions of certain representations of reductive algebraic groups with Frobenius maps
topic Representation Theory
url https://arxiv.org/abs/2404.09495