Abelian group in a topos of sheaves: torsion and essential extensions

We investigate the properties of torsion groups and their essential extensions in the category AbShL of Abellan groups in a topos of sheaves on a locale. We show that every torsion group is a direct sum of its p-primary components and for a torsion group A, the group [A,B] is reduced for any Bε AbSh...

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Main Author: Kiran R. Bhutani
Format: Article
Language:English
Published: Wiley 1989-01-01
Series:International Journal of Mathematics and Mathematical Sciences
Online Access:http://dx.doi.org/10.1155/S0161171289000128
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author Kiran R. Bhutani
author_facet Kiran R. Bhutani
author_sort Kiran R. Bhutani
collection DOAJ
description We investigate the properties of torsion groups and their essential extensions in the category AbShL of Abellan groups in a topos of sheaves on a locale. We show that every torsion group is a direct sum of its p-primary components and for a torsion group A, the group [A,B] is reduced for any Bε AbShL.. We give an example to show that in AbShL the torsion subgroup of an injective group need not be injective. Further we prove that if the locale is Boolean or finite then essential extensions of torsion groups are torsion. Finally we show that for a first countable hausdorff space X essential extensions of torsion groups in AbSh0(X) are torsion iff X is discrete.
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spelling doaj-art-562310bb5ea846af83074227395be3802025-02-03T06:42:29ZengWileyInternational Journal of Mathematics and Mathematical Sciences0161-17121687-04251989-01-01121899810.1155/S0161171289000128Abelian group in a topos of sheaves: torsion and essential extensionsKiran R. Bhutani0Department of Mathematics, The Catholic University of America, Washington, D.C. 20064, USAWe investigate the properties of torsion groups and their essential extensions in the category AbShL of Abellan groups in a topos of sheaves on a locale. We show that every torsion group is a direct sum of its p-primary components and for a torsion group A, the group [A,B] is reduced for any Bε AbShL.. We give an example to show that in AbShL the torsion subgroup of an injective group need not be injective. Further we prove that if the locale is Boolean or finite then essential extensions of torsion groups are torsion. Finally we show that for a first countable hausdorff space X essential extensions of torsion groups in AbSh0(X) are torsion iff X is discrete.http://dx.doi.org/10.1155/S0161171289000128
spellingShingle Kiran R. Bhutani
Abelian group in a topos of sheaves: torsion and essential extensions
International Journal of Mathematics and Mathematical Sciences
title Abelian group in a topos of sheaves: torsion and essential extensions
title_full Abelian group in a topos of sheaves: torsion and essential extensions
title_fullStr Abelian group in a topos of sheaves: torsion and essential extensions
title_full_unstemmed Abelian group in a topos of sheaves: torsion and essential extensions
title_short Abelian group in a topos of sheaves: torsion and essential extensions
title_sort abelian group in a topos of sheaves torsion and essential extensions
url http://dx.doi.org/10.1155/S0161171289000128
work_keys_str_mv AT kiranrbhutani abeliangroupinatoposofsheavestorsionandessentialextensions