Semi-perfect and F-semi-perfect modules

A module is semi-perfect iff every factor module has a projective cover. A module M=A+B (for submodules A and B) is amply supplemented iff there exists a submodule A′ (called a supplement of A) of B such M=A+A′ and A′ is minimal with this property. If B=M then M is supplemented. Kasch and Mares [1]...

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Main Author: David J. Fieldhouse
Format: Article
Language:English
Published: Wiley 1985-01-01
Series:International Journal of Mathematics and Mathematical Sciences
Subjects:
Online Access:http://dx.doi.org/10.1155/S0161171285000588
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author David J. Fieldhouse
author_facet David J. Fieldhouse
author_sort David J. Fieldhouse
collection DOAJ
description A module is semi-perfect iff every factor module has a projective cover. A module M=A+B (for submodules A and B) is amply supplemented iff there exists a submodule A′ (called a supplement of A) of B such M=A+A′ and A′ is minimal with this property. If B=M then M is supplemented. Kasch and Mares [1] have shown that the first and last of these conditions are equivalent for projective modules. Here it is shown that an arbitrary module is semi-perfect iff it is (amply) supplemented by supplements which have projective covers, an extension of the result of Kasch and Mares [1]. Corresponding results are obtained for F-semi-perfect modules.
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spelling doaj-art-e406dec631364da398b3571de63d1cb42025-02-03T01:29:07ZengWileyInternational Journal of Mathematics and Mathematical Sciences0161-17121687-04251985-01-018354554810.1155/S0161171285000588Semi-perfect and F-semi-perfect modulesDavid J. Fieldhouse0Department of Mathematics and Statistics, University of Guelph, Guelph N1G 2W1, Ontario, CanadaA module is semi-perfect iff every factor module has a projective cover. A module M=A+B (for submodules A and B) is amply supplemented iff there exists a submodule A′ (called a supplement of A) of B such M=A+A′ and A′ is minimal with this property. If B=M then M is supplemented. Kasch and Mares [1] have shown that the first and last of these conditions are equivalent for projective modules. Here it is shown that an arbitrary module is semi-perfect iff it is (amply) supplemented by supplements which have projective covers, an extension of the result of Kasch and Mares [1]. Corresponding results are obtained for F-semi-perfect modules.http://dx.doi.org/10.1155/S0161171285000588F-semi-perfect moduleprojective coversemi-perfect modulesmall submodulesupplement.
spellingShingle David J. Fieldhouse
Semi-perfect and F-semi-perfect modules
International Journal of Mathematics and Mathematical Sciences
F-semi-perfect module
projective cover
semi-perfect module
small submodule
supplement.
title Semi-perfect and F-semi-perfect modules
title_full Semi-perfect and F-semi-perfect modules
title_fullStr Semi-perfect and F-semi-perfect modules
title_full_unstemmed Semi-perfect and F-semi-perfect modules
title_short Semi-perfect and F-semi-perfect modules
title_sort semi perfect and f semi perfect modules
topic F-semi-perfect module
projective cover
semi-perfect module
small submodule
supplement.
url http://dx.doi.org/10.1155/S0161171285000588
work_keys_str_mv AT davidjfieldhouse semiperfectandfsemiperfectmodules