Morphisms of character varieties

Fuente: arXiv
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Main Author: Cotner, Sean
Format: Preprint
Published: 2023
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_version_ 1866929361198776320
author Cotner, Sean
author_facet Cotner, Sean
contents Let $k$ be a field, let $H \subset G$ be (possibly disconnected) reductive groups over $k$, and let $Γ$ be a finitely generated group. Vinberg and Martin have shown that the induced morphism of character varieties \[ \underline{\mathrm{Hom}}_{k\textrm{-gp}}(Γ, H)//H \to \underline{\mathrm{Hom}}_{k\textrm{-gp}}(Γ, G)//G \] is finite. In this note, we generalize this result (with a significantly different proof) by replacing $k$ with an arbitrary locally noetherian scheme, answering a question of Dat. Along the way, we use Bruhat-Tits theory to establish a few apparently new results about integral models of reductive groups over discrete valuation rings.
format Preprint
id arxiv_https___arxiv_org_abs_2304_10135
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Morphisms of character varieties
Cotner, Sean
Representation Theory
Algebraic Geometry
20G35, 14L30, 14L15
Let $k$ be a field, let $H \subset G$ be (possibly disconnected) reductive groups over $k$, and let $Γ$ be a finitely generated group. Vinberg and Martin have shown that the induced morphism of character varieties \[ \underline{\mathrm{Hom}}_{k\textrm{-gp}}(Γ, H)//H \to \underline{\mathrm{Hom}}_{k\textrm{-gp}}(Γ, G)//G \] is finite. In this note, we generalize this result (with a significantly different proof) by replacing $k$ with an arbitrary locally noetherian scheme, answering a question of Dat. Along the way, we use Bruhat-Tits theory to establish a few apparently new results about integral models of reductive groups over discrete valuation rings.
title Morphisms of character varieties
topic Representation Theory
Algebraic Geometry
20G35, 14L30, 14L15
url https://arxiv.org/abs/2304.10135