On the direct sum of dual-square-free modules

A module \(M\) is called square-free if it contains no non-zero isomorphic submodules \(A\) and \(B\) with \(A \cap B =0\). Dually, \(M\) is called dual-square-free if \(M\) has no proper submodules \(A\) and \(B\) with \(M =A +B\) and \(M/A \cong M/B\). In this paper we show that if \(M = \oplus _{...

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Дата:2022
Автори: Ibrahim, Y., Yousif, M.
Формат: Стаття
Мова:English
Опубліковано: Lugansk National Taras Shevchenko University 2022
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Онлайн доступ:https://admjournal.luguniv.edu.ua/index.php/adm/article/view/1807
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Назва журналу:Algebra and Discrete Mathematics

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Algebra and Discrete Mathematics
id oai:ojs.admjournal.luguniv.edu.ua:article-1807
record_format ojs
spelling oai:ojs.admjournal.luguniv.edu.ua:article-18072022-06-15T04:49:44Z On the direct sum of dual-square-free modules Ibrahim, Y. Yousif, M. square-free and dual-square-free modules, abelian and quasi-duo rings Primary 16D40, 16D50, 16D60; Secondary 16L30, 16L60, 16P20, 16P40, 16P60 A module \(M\) is called square-free if it contains no non-zero isomorphic submodules \(A\) and \(B\) with \(A \cap B =0\). Dually, \(M\) is called dual-square-free if \(M\) has no proper submodules \(A\) and \(B\) with \(M =A +B\) and \(M/A \cong M/B\). In this paper we show that if \(M = \oplus _{i \in I}M_{i}\), then \(M\) is square-free iff each \(M_{i}\) is square-free and \(M_{j}\) and \( \oplus _{j \neq i \in I}M_{i}\) are orthogonal. Dually, if \(M  = \oplus _{i =1}^{n}M_{i}\), then \(M\) is dual-square-free iff each \(M_{i}\) is dual-square-free, \(1 \leqslant i \leqslant n\), and \(M_{j}\) and \( \oplus _{i \neq j}^{n}M_{i}\) are factor-orthogonal. Moreover, in the infinite case, we show that if \(M = \oplus _{i \in I}S_{i}\) is a direct sum of non-isomorphic simple modules, then \(M\) is a dual-square-free. In particular, if \(M =A \oplus B\) where \(A\) is dual-square-free and \(B = \oplus _{i \in I}S_{i}\) is a direct sum of non-isomorphic simple modules, then \(M\) is dual-square-free iff \(A\) and \(B\) are factor-orthogonal; this extends an earlier result by the authors in [2, Proposition 2.8]. Lugansk National Taras Shevchenko University 2022-06-15 Article Article Peer-reviewed Article application/pdf https://admjournal.luguniv.edu.ua/index.php/adm/article/view/1807 10.12958/adm1807 Algebra and Discrete Mathematics; Vol 33, No 1 (2022) 2415-721X 1726-3255 en https://admjournal.luguniv.edu.ua/index.php/adm/article/view/1807/pdf https://admjournal.luguniv.edu.ua/index.php/adm/article/downloadSuppFile/1807/865 Copyright (c) 2022 Algebra and Discrete Mathematics
institution Algebra and Discrete Mathematics
collection OJS
language English
topic square-free and dual-square-free modules
abelian and quasi-duo rings
Primary 16D40
16D50
16D60; Secondary 16L30
16L60
16P20
16P40
16P60
spellingShingle square-free and dual-square-free modules
abelian and quasi-duo rings
Primary 16D40
16D50
16D60; Secondary 16L30
16L60
16P20
16P40
16P60
Ibrahim, Y.
Yousif, M.
On the direct sum of dual-square-free modules
topic_facet square-free and dual-square-free modules
abelian and quasi-duo rings
Primary 16D40
16D50
16D60; Secondary 16L30
16L60
16P20
16P40
16P60
format Article
author Ibrahim, Y.
Yousif, M.
author_facet Ibrahim, Y.
Yousif, M.
author_sort Ibrahim, Y.
title On the direct sum of dual-square-free modules
title_short On the direct sum of dual-square-free modules
title_full On the direct sum of dual-square-free modules
title_fullStr On the direct sum of dual-square-free modules
title_full_unstemmed On the direct sum of dual-square-free modules
title_sort on the direct sum of dual-square-free modules
description A module \(M\) is called square-free if it contains no non-zero isomorphic submodules \(A\) and \(B\) with \(A \cap B =0\). Dually, \(M\) is called dual-square-free if \(M\) has no proper submodules \(A\) and \(B\) with \(M =A +B\) and \(M/A \cong M/B\). In this paper we show that if \(M = \oplus _{i \in I}M_{i}\), then \(M\) is square-free iff each \(M_{i}\) is square-free and \(M_{j}\) and \( \oplus _{j \neq i \in I}M_{i}\) are orthogonal. Dually, if \(M  = \oplus _{i =1}^{n}M_{i}\), then \(M\) is dual-square-free iff each \(M_{i}\) is dual-square-free, \(1 \leqslant i \leqslant n\), and \(M_{j}\) and \( \oplus _{i \neq j}^{n}M_{i}\) are factor-orthogonal. Moreover, in the infinite case, we show that if \(M = \oplus _{i \in I}S_{i}\) is a direct sum of non-isomorphic simple modules, then \(M\) is a dual-square-free. In particular, if \(M =A \oplus B\) where \(A\) is dual-square-free and \(B = \oplus _{i \in I}S_{i}\) is a direct sum of non-isomorphic simple modules, then \(M\) is dual-square-free iff \(A\) and \(B\) are factor-orthogonal; this extends an earlier result by the authors in [2, Proposition 2.8].
publisher Lugansk National Taras Shevchenko University
publishDate 2022
url https://admjournal.luguniv.edu.ua/index.php/adm/article/view/1807
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