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Main Author: Huebschmann, Johannes
Format: Preprint
Published: 2024
Subjects:
Online Access:https://arxiv.org/abs/2403.15900
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author Huebschmann, Johannes
author_facet Huebschmann, Johannes
contents This is an overview of the idea of a crossed module. For a group, the triple that consists of the group, its group of automorphisms, and the canonical homomorphism from the group to its group of automorphisms constitutes a crossed module. Crossed modules arise from the identities among the relations of the presentation of a group, from the extension problem for groups and, more generally, in low dimensional topology. Also, the (successful) attempt to extend the idea of a normal extension of commutative fields to the realm of non-commutative algebras leads to crossed modules. Crossed modules appear implicitly in a forgotten paper by A. Turing which in principle settles the extension problem for groups. Crossed modules make perfect sense for Lie algebras.
format Preprint
id arxiv_https___arxiv_org_abs_2403_15900
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Crossed modules
Huebschmann, Johannes
Group Theory
Algebraic Topology
01A60 12G05 18G45 20J05 57M10
This is an overview of the idea of a crossed module. For a group, the triple that consists of the group, its group of automorphisms, and the canonical homomorphism from the group to its group of automorphisms constitutes a crossed module. Crossed modules arise from the identities among the relations of the presentation of a group, from the extension problem for groups and, more generally, in low dimensional topology. Also, the (successful) attempt to extend the idea of a normal extension of commutative fields to the realm of non-commutative algebras leads to crossed modules. Crossed modules appear implicitly in a forgotten paper by A. Turing which in principle settles the extension problem for groups. Crossed modules make perfect sense for Lie algebras.
title Crossed modules
topic Group Theory
Algebraic Topology
01A60 12G05 18G45 20J05 57M10
url https://arxiv.org/abs/2403.15900