An affineness criterion for algebraic groups and applications

Fuente: arXiv
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Autores principales: de Salas, C. Sancho, de Salas, F. Sancho, de Salas, J. B. Sancho
Formato: Preprint
Publicado: 2018
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author de Salas, C. Sancho
de Salas, F. Sancho
de Salas, J. B. Sancho
author_facet de Salas, C. Sancho
de Salas, F. Sancho
de Salas, J. B. Sancho
contents We prove that a smooth and connected algebraic group $G$ is affine if and only if any invertible sheaf on any normal $G$-variety is $G$-invariant. For the proof, a key ingredient is the following result: if $G$ is a connected and smooth algebraic group and $\mathcal L$ is a $G$-invariant invertible sheaf on a $G$-variety $X$, then the action of $G$ on $X$ extends to a projective action on the complete linear ${\mathbb P}(H^0(X,{\mathcal L})$. As an application of the affineness criterion, we give a new and simple proof of Chevalley-Barsotti Theorem on the structure of algebraic groups.
format Preprint
id arxiv_https___arxiv_org_abs_1802_05901
institution arXiv
publishDate 2018
record_format arxiv
spellingShingle An affineness criterion for algebraic groups and applications
de Salas, C. Sancho
de Salas, F. Sancho
de Salas, J. B. Sancho
Algebraic Geometry
14L17, 14L30, 14L15
We prove that a smooth and connected algebraic group $G$ is affine if and only if any invertible sheaf on any normal $G$-variety is $G$-invariant. For the proof, a key ingredient is the following result: if $G$ is a connected and smooth algebraic group and $\mathcal L$ is a $G$-invariant invertible sheaf on a $G$-variety $X$, then the action of $G$ on $X$ extends to a projective action on the complete linear ${\mathbb P}(H^0(X,{\mathcal L})$. As an application of the affineness criterion, we give a new and simple proof of Chevalley-Barsotti Theorem on the structure of algebraic groups.
title An affineness criterion for algebraic groups and applications
topic Algebraic Geometry
14L17, 14L30, 14L15
url https://arxiv.org/abs/1802.05901