Splitting rational incomplete Mackey functors

Fuente: arXiv
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Autori principali: Barnes, David, Hill, Michael A., Kedziorek, Magdalena
Natura: Preprint
Pubblicazione: 2024
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author Barnes, David
Hill, Michael A.
Kedziorek, Magdalena
author_facet Barnes, David
Hill, Michael A.
Kedziorek, Magdalena
contents Inspired by equivariant homotopy theory, equivariant algebra studies generalisations of G-Mackey functors that do not have all transfer maps (also known as induction maps), for G a finite group. These incomplete Mackey functors have interesting and subtle properties that are more complicated than classical algebra. The levels of incompleteness that occur are indexed by simple combinatorial data known as transfer systems for G, which are refinements of the subgroup relation satisfying certain axioms. The aim of this paper is to generalise the Greenlees--May and Thevenaz--Webb splitting result of rational G-Mackey functors to the incomplete case. By calculating idempotents of the rational incomplete Burnside ring of G, we find the maximal splitting of the category of rational incomplete G-Mackey functors. These splittings are determined by maps of the form H to G in the transfer system. We give an intrinsic definition of the split pieces beyond the idempotent description in order to understand what is the minimal information needed to determine an arbitrary rational incomplete G-Mackey functor. We end the paper with a series of examples of possible splittings and illustrate how simpler transfer systems have fewer terms in the splitting but the split pieces are more complicated.
format Preprint
id arxiv_https___arxiv_org_abs_2410_10962
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Splitting rational incomplete Mackey functors
Barnes, David
Hill, Michael A.
Kedziorek, Magdalena
Algebraic Topology
Representation Theory
55P91 (Primary) 55N91, 19A22, 18B10 (Secondary)
Inspired by equivariant homotopy theory, equivariant algebra studies generalisations of G-Mackey functors that do not have all transfer maps (also known as induction maps), for G a finite group. These incomplete Mackey functors have interesting and subtle properties that are more complicated than classical algebra. The levels of incompleteness that occur are indexed by simple combinatorial data known as transfer systems for G, which are refinements of the subgroup relation satisfying certain axioms. The aim of this paper is to generalise the Greenlees--May and Thevenaz--Webb splitting result of rational G-Mackey functors to the incomplete case. By calculating idempotents of the rational incomplete Burnside ring of G, we find the maximal splitting of the category of rational incomplete G-Mackey functors. These splittings are determined by maps of the form H to G in the transfer system. We give an intrinsic definition of the split pieces beyond the idempotent description in order to understand what is the minimal information needed to determine an arbitrary rational incomplete G-Mackey functor. We end the paper with a series of examples of possible splittings and illustrate how simpler transfer systems have fewer terms in the splitting but the split pieces are more complicated.
title Splitting rational incomplete Mackey functors
topic Algebraic Topology
Representation Theory
55P91 (Primary) 55N91, 19A22, 18B10 (Secondary)
url https://arxiv.org/abs/2410.10962