Configured locally smooth cohomology and $\mathbb{Q}/\mathbb{Z}$-torsion in $H_3$ of diffeomorphism groups

Fuente: arXiv
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Main Author: Nosaka, Takefumi
Format: Preprint
Published: 2026
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author Nosaka, Takefumi
author_facet Nosaka, Takefumi
contents We introduce configured group cohomology, a variant of locally smooth cohomology built from well-configured tuples and geometric fillings. This framework yields explicit locally smooth $\R/\Z$-valued $3$-cocycles of Chern--Simons type on diffeomorphism groups preserving geometric structures. As an application we show that, for several such groups, the third group homology contains a subgroup isomorphic to $\Q/\Z$.
format Preprint
id arxiv_https___arxiv_org_abs_2601_07230
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Configured locally smooth cohomology and $\mathbb{Q}/\mathbb{Z}$-torsion in $H_3$ of diffeomorphism groups
Nosaka, Takefumi
Geometric Topology
Algebraic Topology
57M50, 57S05, 58D05, 22E65, 20J06
We introduce configured group cohomology, a variant of locally smooth cohomology built from well-configured tuples and geometric fillings. This framework yields explicit locally smooth $\R/\Z$-valued $3$-cocycles of Chern--Simons type on diffeomorphism groups preserving geometric structures. As an application we show that, for several such groups, the third group homology contains a subgroup isomorphic to $\Q/\Z$.
title Configured locally smooth cohomology and $\mathbb{Q}/\mathbb{Z}$-torsion in $H_3$ of diffeomorphism groups
topic Geometric Topology
Algebraic Topology
57M50, 57S05, 58D05, 22E65, 20J06
url https://arxiv.org/abs/2601.07230