<p>A right <i>R</i>-module <i>M</i> is said to be dual-ADS if for every decomposition <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40306_2024_562_Article_IEq4.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="91" /> </InlineMediaObject> <EquationSource Format="TEX">\(M=A\oplus B\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>M</mi> <mo>=</mo> <mi>A</mi> <mo>⊕</mo> <mi>B</mi> </mrow> </math></EquationSource> </InlineEquation> then <i>A</i> and <i>B</i> are mutually projective. The class of ADS*-modules contains the class of dual-ADS modules. In this article, we study several properties of these modules. It is shown that a module <i>M</i> is dual-ADS if and only if for any direct summand <i>S</i> and <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40306_2024_562_Article_IEq5.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="60" /> </InlineMediaObject> <EquationSource Format="TEX">\(T^\prime \le M\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>T</mi> <mo>′</mo> </msup> <mo>≤</mo> <mi>M</mi> </mrow> </math></EquationSource> </InlineEquation> with <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40306_2024_562_Article_IEq6.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="51" /> </InlineMediaObject> <EquationSource Format="TEX">\(T^\prime +S\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>T</mi> <mo>′</mo> </msup> <mo>+</mo> <mi>S</mi> </mrow> </math></EquationSource> </InlineEquation> a direct summand of <i>M</i>, then <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40306_2024_562_Article_IEq7.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(T^\prime \)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>T</mi> <mo>′</mo> </msup> </math></EquationSource> </InlineEquation> contains a direct complement of <i>S</i> in <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40306_2024_562_Article_IEq8.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="51" /> </InlineMediaObject> <EquationSource Format="TEX">\(T^\prime +S\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>T</mi> <mo>′</mo> </msup> <mo>+</mo> <mi>S</mi> </mrow> </math></EquationSource> </InlineEquation>. A generalization of dual-ADS modules is considered, namely, ADS<InlineEquation ID="IEq9"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40306_2024_562_Article_IEq9.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="11" /> </InlineMediaObject> <EquationSource Format="TEX">\(^\#\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mo>#</mo> </mmultiscripts> </math></EquationSource> </InlineEquation>-modules. It is shown that a module <i>M</i> is ADS<InlineEquation ID="IEq10"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40306_2024_562_Article_IEq10.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="11" /> </InlineMediaObject> <EquationSource Format="TEX">\(^\#\)</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mo>#</mo> </mmultiscripts> </math></EquationSource> </InlineEquation> if and only if for any direct summand <i>S</i> of <i>M</i>, and any weak supplement <InlineEquation ID="IEq11"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40306_2024_562_Article_IEq11.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(T^\prime \)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>T</mi> <mo>′</mo> </msup> </math></EquationSource> </InlineEquation> of <i>S</i> in <InlineEquation ID="IEq12"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40306_2024_562_Article_IEq12.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="51" /> </InlineMediaObject> <EquationSource Format="TEX">\(T^\prime +S\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>T</mi> <mo>′</mo> </msup> <mo>+</mo> <mi>S</mi> </mrow> </math></EquationSource> </InlineEquation> such that <InlineEquation ID="IEq13"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40306_2024_562_Article_IEq13.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="51" /> </InlineMediaObject> <EquationSource Format="TEX">\(T^\prime +S\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>T</mi> <mo>′</mo> </msup> <mo>+</mo> <mi>S</mi> </mrow> </math></EquationSource> </InlineEquation> is a direct summand of <i>M</i>, then <InlineEquation ID="IEq14"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40306_2024_562_Article_IEq14.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(T^\prime \)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>T</mi> <mo>′</mo> </msup> </math></EquationSource> </InlineEquation> contains a direct complement of <i>S</i> in <InlineEquation ID="IEq15"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40306_2024_562_Article_IEq15.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="51" /> </InlineMediaObject> <EquationSource Format="TEX">\(T^\prime +S\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>T</mi> <mo>′</mo> </msup> <mo>+</mo> <mi>S</mi> </mrow> </math></EquationSource> </InlineEquation>.</p>

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Dual-ADS, ADS\(^\#\) and ADS* Modules

  • Abyzov Adel Nailevich,
  • Bui Tien Dat,
  • Truong Cong Quynh

摘要

A right R-module M is said to be dual-ADS if for every decomposition \(M=A\oplus B\) M = A B then A and B are mutually projective. The class of ADS*-modules contains the class of dual-ADS modules. In this article, we study several properties of these modules. It is shown that a module M is dual-ADS if and only if for any direct summand S and \(T^\prime \le M\) T M with \(T^\prime +S\) T + S a direct summand of M, then \(T^\prime \) T contains a direct complement of S in \(T^\prime +S\) T + S . A generalization of dual-ADS modules is considered, namely, ADS \(^\#\) # -modules. It is shown that a module M is ADS \(^\#\) # if and only if for any direct summand S of M, and any weak supplement \(T^\prime \) T of S in \(T^\prime +S\) T + S such that \(T^\prime +S\) T + S is a direct summand of M, then \(T^\prime \) T contains a direct complement of S in \(T^\prime +S\) T + S .