Global representation theory: Homological foundations

Fuente: arXiv
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Main Authors: Barrero, Miguel, Barthel, Tobias, Pol, Luca, Strickland, Neil, Williamson, Jordan
Format: Preprint
Published: 2025
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_version_ 1866910235415805952
author Barrero, Miguel
Barthel, Tobias
Pol, Luca
Strickland, Neil
Williamson, Jordan
author_facet Barrero, Miguel
Barthel, Tobias
Pol, Luca
Strickland, Neil
Williamson, Jordan
contents A global representation is a compatible collection of representations of the outer automorphism groups of the groups belonging to some collection of finite groups $\mathscr{U}$. Global representations assemble into an abelian category $\mathsf{A}(\mathscr{U})$, simultaneously generalising classical representation theory and the category of VI-modules appearing in the representation theory of the general linear groups. In this paper we establish homological foundations of its derived category $\mathsf{D}(\mathscr{U})$. We prove that any complex of projective global representations is DG-projective, and hence conclude that the derived category admits an explicit model as the homotopy category of projective global representations. We show that from a tensor-triangular perspective it exhibits some unusual features: for example, there are very few dualizable objects and in general many more compact objects. Under more restrictive conditions on the family $\mathscr{U}$, we then construct torsion-free classes for global representations which encode certain growth properties in $\mathscr{U}$. This lays the foundations for a detailed study of the tensor-triangular geometry of derived global representations which we pursue in forthcoming work.
format Preprint
id arxiv_https___arxiv_org_abs_2505_21449
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Global representation theory: Homological foundations
Barrero, Miguel
Barthel, Tobias
Pol, Luca
Strickland, Neil
Williamson, Jordan
Representation Theory
Algebraic Topology
Category Theory
A global representation is a compatible collection of representations of the outer automorphism groups of the groups belonging to some collection of finite groups $\mathscr{U}$. Global representations assemble into an abelian category $\mathsf{A}(\mathscr{U})$, simultaneously generalising classical representation theory and the category of VI-modules appearing in the representation theory of the general linear groups. In this paper we establish homological foundations of its derived category $\mathsf{D}(\mathscr{U})$. We prove that any complex of projective global representations is DG-projective, and hence conclude that the derived category admits an explicit model as the homotopy category of projective global representations. We show that from a tensor-triangular perspective it exhibits some unusual features: for example, there are very few dualizable objects and in general many more compact objects. Under more restrictive conditions on the family $\mathscr{U}$, we then construct torsion-free classes for global representations which encode certain growth properties in $\mathscr{U}$. This lays the foundations for a detailed study of the tensor-triangular geometry of derived global representations which we pursue in forthcoming work.
title Global representation theory: Homological foundations
topic Representation Theory
Algebraic Topology
Category Theory
url https://arxiv.org/abs/2505.21449