Skew Hecke Algebras

Fuente: arXiv
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Main Authors: Waldron, James, Loveridge, Leon Deryck
Format: Preprint
Published: 2023
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author Waldron, James
Loveridge, Leon Deryck
author_facet Waldron, James
Loveridge, Leon Deryck
contents Let $G$ be a finite group, $H \le G$ a subgroup, $R$ a commutative ring, $A$ an $R$-algebra, and $α$ an action of $G$ on $A$ by $R$-algebra automorphisms. We study the associated \emph{skew Hecke algebra} $\mathcal{H}_{R}(G,H,A,α)$, which is the convolution algebra of $H$-invariant functions from $G/H$ to $A$. We prove for skew Hecke algebras a number of common generalisations of results about skew group algebras and results about Hecke algebras of finite groups. We show that skew Hecke algebras admit a certain double coset decomposition. We construct an isomorphism from $\mathcal{H}_{R}(G,H,A,α)$ to the algebra of $G$-invariants in the tensor product $A \otimes \mathrm{End}_{R} ( \mathrm{Ind}_{H}^{G} R )$. We show that if $|H|$ is a unit in $A$, then $\mathcal{H}_{R}(G,H,A,α)$ is isomorphic to a corner ring inside the skew group algebra $A \rtimes G$. Alongside our main results, we show that the construction of skew Hecke algebras is compatible with certain group-theoretic operations, restriction and extension of scalars, certain cocycle perturbations of the action, gradings and filtrations, and the formation of opposite algebras. The main results are illustrated in the case where $G = S_3$, $H = S_2$, and $α$ is the natural permutation action of $S_3$ on the polynomial algebra $R[x_1,x_2,x_3]$.
format Preprint
id arxiv_https___arxiv_org_abs_2311_09038
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Skew Hecke Algebras
Waldron, James
Loveridge, Leon Deryck
Rings and Algebras
16S35 (Primary) 20C08 (Secondary)
Let $G$ be a finite group, $H \le G$ a subgroup, $R$ a commutative ring, $A$ an $R$-algebra, and $α$ an action of $G$ on $A$ by $R$-algebra automorphisms. We study the associated \emph{skew Hecke algebra} $\mathcal{H}_{R}(G,H,A,α)$, which is the convolution algebra of $H$-invariant functions from $G/H$ to $A$. We prove for skew Hecke algebras a number of common generalisations of results about skew group algebras and results about Hecke algebras of finite groups. We show that skew Hecke algebras admit a certain double coset decomposition. We construct an isomorphism from $\mathcal{H}_{R}(G,H,A,α)$ to the algebra of $G$-invariants in the tensor product $A \otimes \mathrm{End}_{R} ( \mathrm{Ind}_{H}^{G} R )$. We show that if $|H|$ is a unit in $A$, then $\mathcal{H}_{R}(G,H,A,α)$ is isomorphic to a corner ring inside the skew group algebra $A \rtimes G$. Alongside our main results, we show that the construction of skew Hecke algebras is compatible with certain group-theoretic operations, restriction and extension of scalars, certain cocycle perturbations of the action, gradings and filtrations, and the formation of opposite algebras. The main results are illustrated in the case where $G = S_3$, $H = S_2$, and $α$ is the natural permutation action of $S_3$ on the polynomial algebra $R[x_1,x_2,x_3]$.
title Skew Hecke Algebras
topic Rings and Algebras
16S35 (Primary) 20C08 (Secondary)
url https://arxiv.org/abs/2311.09038