Configuration spaces on a wedge of spheres and Hochschild-Pirashvili homology

Fuente: arXiv
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Autori principali: Gadish, Nir, Hainaut, Louis
Natura: Preprint
Pubblicazione: 2022
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author Gadish, Nir
Hainaut, Louis
author_facet Gadish, Nir
Hainaut, Louis
contents We study the compactly supported rational cohomology of configuration spaces of points on wedges of spheres, equipped with natural actions of the symmetric group and the group $Out(F_g)$ of outer automorphisms of the free group. These representations show up in seemingly unrelated parts of mathematics, from cohomology of moduli spaces of curves to polynomial functors on free groups and Hochschild-Pirashvili cohomology. We show that these cohomology representations form a polynomial functor, and use various geometric models to compute many of its composition factors. We further compute the composition factors completely for all configurations of $n\leq 10$ particles. An application of this analysis is a new super-exponential lower bound on the symmetric group action on the weight $0$ component of $H^*_c(M_{2,n})$.
format Preprint
id arxiv_https___arxiv_org_abs_2202_12494
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Configuration spaces on a wedge of spheres and Hochschild-Pirashvili homology
Gadish, Nir
Hainaut, Louis
Algebraic Topology
Representation Theory
55R80, 14H10, 14Q05, 13D03
We study the compactly supported rational cohomology of configuration spaces of points on wedges of spheres, equipped with natural actions of the symmetric group and the group $Out(F_g)$ of outer automorphisms of the free group. These representations show up in seemingly unrelated parts of mathematics, from cohomology of moduli spaces of curves to polynomial functors on free groups and Hochschild-Pirashvili cohomology. We show that these cohomology representations form a polynomial functor, and use various geometric models to compute many of its composition factors. We further compute the composition factors completely for all configurations of $n\leq 10$ particles. An application of this analysis is a new super-exponential lower bound on the symmetric group action on the weight $0$ component of $H^*_c(M_{2,n})$.
title Configuration spaces on a wedge of spheres and Hochschild-Pirashvili homology
topic Algebraic Topology
Representation Theory
55R80, 14H10, 14Q05, 13D03
url https://arxiv.org/abs/2202.12494