Baer-like decompositions of modules. (Q1409618)

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scientific article; zbMATH DE number 1993639
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Baer-like decompositions of modules.
scientific article; zbMATH DE number 1993639

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    Baer-like decompositions of modules. (English)
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    16 October 2003
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    \textit{R. Baer} [in J. Algebra 20, 38-56 (1972; Zbl 0225.20018)], proved the following result: suppose that \(\mathcal X\) is a local formation of finite groups and \(A\) is a normal subgroup of a finite group \(G\) such that \(Q=G/C_G (A)\) is \(\mathcal X\)-nilpotent. Then \(A=(A\cap HZ_{\mathcal X}(G))\times(A\cap HE_{\mathcal X}(G))\). Here, \(HZ_{\mathcal X}(G)\) is the \(\mathcal X\)-hypercenter of \(G\), the maximal normal subgroup of \(G\) with the property that all its \(G\)-chief factors \(C/B\) have \(G/C_G (C/B)\in{\mathcal X}\), and \(HE_{\mathcal X}(G)\) is the \(\mathcal X\)-hypereccenter of \(G\), the maximal normal subgroup of \(G\) with the property that all its \(G\)-chief factors \(C/B\) have \(G/C_G (C/B)\notin{\mathcal X}\). A finite group \(G\) is \(\mathcal X\)-nilpotent if \(HZ_{\mathcal X}(G)=G\). The present paper is concerned with Baer decompositions of the above nature, but for Artinian \(DG\)-modules rather than groups. Here, \(D\) is a Dedekind domain and \(G\) is an (infinite) \(\mathcal X\)-hypercentral group for a formation of finite groups \(\mathcal X\). The precise results obtained require further notation which makes it inappropriate to state them in detail here.
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    formations of finite groups
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    hypercentral groups
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    Artinian modules
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    group rings
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    Baer decompositions
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    direct decompositions
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    chief factors
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