Centrality of $\mathrm K_2$ for Chevalley groups: a pro-group approach

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Main Authors: Lavrenov, Andrei, Sinchuk, Sergey, Voronetsky, Egor
Format: Preprint
Published: 2020
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author Lavrenov, Andrei
Sinchuk, Sergey
Voronetsky, Egor
author_facet Lavrenov, Andrei
Sinchuk, Sergey
Voronetsky, Egor
contents We prove the centrality of $\mathrm{K}_2 (\mathsf{F}_4, \,R)$ for an arbitrary commutative ring $R$. This completes the proof of the centrality of $\mathrm K_2(Φ,\, R)$ for any root system $Φ$ of rank $\geq 3$. Our proof uses only elementary localization techniques reformulated in terms of pro-groups. Another new result of the paper is the construction of a crossed module on the canonical homomorphism $\mathrm{St}(Φ, R) \to \mathrm{G}_\mathrm{sc}(Φ, R)$, which has not been known previouly for exceptional $Φ$.
format Preprint
id arxiv_https___arxiv_org_abs_2009_03999
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle Centrality of $\mathrm K_2$ for Chevalley groups: a pro-group approach
Lavrenov, Andrei
Sinchuk, Sergey
Voronetsky, Egor
Group Theory
19C09, 20G35, 20H05
We prove the centrality of $\mathrm{K}_2 (\mathsf{F}_4, \,R)$ for an arbitrary commutative ring $R$. This completes the proof of the centrality of $\mathrm K_2(Φ,\, R)$ for any root system $Φ$ of rank $\geq 3$. Our proof uses only elementary localization techniques reformulated in terms of pro-groups. Another new result of the paper is the construction of a crossed module on the canonical homomorphism $\mathrm{St}(Φ, R) \to \mathrm{G}_\mathrm{sc}(Φ, R)$, which has not been known previouly for exceptional $Φ$.
title Centrality of $\mathrm K_2$ for Chevalley groups: a pro-group approach
topic Group Theory
19C09, 20G35, 20H05
url https://arxiv.org/abs/2009.03999