Structure of Hecke algebras arising from types

Fuente: arXiv
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Autori principali: Adler, Jeffrey D., Fintzen, Jessica, Mishra, Manish, Ohara, Kazuma
Natura: Preprint
Pubblicazione: 2024
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author Adler, Jeffrey D.
Fintzen, Jessica
Mishra, Manish
Ohara, Kazuma
author_facet Adler, Jeffrey D.
Fintzen, Jessica
Mishra, Manish
Ohara, Kazuma
contents Let $G$ denote a connected reductive group over a nonarchimedean local field $F$ of residue characteristic $p$, and let $\mathcal{C}$ denote an algebraically closed field of characteristic $\ell \neq p$. If $ρ$ is an irreducible, smooth $\mathcal{C}$-representation of a compact, open subgroup $K$ of $G(F)$, then the pair $(K,ρ)$ gives rise to a Hecke algebra $\mathcal{H}(G(F),(K, ρ))$. For a large class of pairs $(K,ρ)$, we show that $\mathcal{H}(G(F),(K, ρ))$ is a semi-direct product of an affine Hecke algebra with explicit parameters with a twisted group algebra, and that it is isomorphic to $\mathcal{H}(G^0(F),(K^0, ρ^0))$ for some reductive subgroup $G^0 \subset G$ with compact, open subgroup $K^0$ and depth-zero representation $ρ^0$ of $K^0$. The class of pairs that we consider includes all depth-zero types. In describing their Hecke algebras, we thus recover a result of Morris as a special case. In a second paper, we will show that our class also contains all the types constructed by Kim and Yu, and hence we obtain as a corollary that arbitrary Bernstein blocks are equivalent to depth-zero Bernstein blocks under minor tameness assumptions. The pairs to which our results apply are described in an axiomatic way so that the results can be applied to other constructions of types by only verifying that the relevant axioms are satisfied. The Hecke algebra isomorphisms are given in an explicit manner and are support preserving.
format Preprint
id arxiv_https___arxiv_org_abs_2408_07801
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Structure of Hecke algebras arising from types
Adler, Jeffrey D.
Fintzen, Jessica
Mishra, Manish
Ohara, Kazuma
Representation Theory
Number Theory
Let $G$ denote a connected reductive group over a nonarchimedean local field $F$ of residue characteristic $p$, and let $\mathcal{C}$ denote an algebraically closed field of characteristic $\ell \neq p$. If $ρ$ is an irreducible, smooth $\mathcal{C}$-representation of a compact, open subgroup $K$ of $G(F)$, then the pair $(K,ρ)$ gives rise to a Hecke algebra $\mathcal{H}(G(F),(K, ρ))$. For a large class of pairs $(K,ρ)$, we show that $\mathcal{H}(G(F),(K, ρ))$ is a semi-direct product of an affine Hecke algebra with explicit parameters with a twisted group algebra, and that it is isomorphic to $\mathcal{H}(G^0(F),(K^0, ρ^0))$ for some reductive subgroup $G^0 \subset G$ with compact, open subgroup $K^0$ and depth-zero representation $ρ^0$ of $K^0$. The class of pairs that we consider includes all depth-zero types. In describing their Hecke algebras, we thus recover a result of Morris as a special case. In a second paper, we will show that our class also contains all the types constructed by Kim and Yu, and hence we obtain as a corollary that arbitrary Bernstein blocks are equivalent to depth-zero Bernstein blocks under minor tameness assumptions. The pairs to which our results apply are described in an axiomatic way so that the results can be applied to other constructions of types by only verifying that the relevant axioms are satisfied. The Hecke algebra isomorphisms are given in an explicit manner and are support preserving.
title Structure of Hecke algebras arising from types
topic Representation Theory
Number Theory
url https://arxiv.org/abs/2408.07801