<p>Let <i>R</i> be a commutative ring with identity and <i>M</i> be an <i>R</i>-module. For a non-negative integer <i>d</i> and an ideal <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\frak{b}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mi mathvariant="fraktur">b</mi> </mrow> </math></EquationSource> </InlineEquation> of <i>R</i>, the concept of <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\((d,\frak{b})\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mo stretchy="false">(</mo> <mi>d</mi> <mo>,</mo> <mrow> <mi mathvariant="fraktur">b</mi> </mrow> <mo mathvariant="fraktur" stretchy="false">)</mo> </math></EquationSource> </InlineEquation>-injectivity in the category of <i>R</i>-modules is defined. We characterize the <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\((d,\frak{b})\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mo stretchy="false">(</mo> <mi>d</mi> <mo>,</mo> <mrow> <mi mathvariant="fraktur">b</mi> </mrow> <mo mathvariant="fraktur" stretchy="false">)</mo> </math></EquationSource> </InlineEquation>-injective hull of a module <i>M</i> as a submodule of <i>E</i>(<i>M</i>). Then we focus on the case when the ring <i>R</i> is Noetherian and see the connection with some modules caused by some ideal transform functor <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(T_{(d,\frak{b})}(-)\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <msub> <mi>T</mi> <mrow> <mo stretchy="false">(</mo> <mi>d</mi> <mo>,</mo> <mrow> <mi mathvariant="fraktur">b</mi> </mrow> <mo mathvariant="fraktur" stretchy="false">)</mo> </mrow> </msub> <mo stretchy="false">(</mo> <mo>−</mo> <mo stretchy="false">)</mo> </math></EquationSource> </InlineEquation> and some local cohomology functors <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(H_{(d,\frak{b})}^{i}(-)\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <msubsup> <mi>H</mi> <mrow> <mo stretchy="false">(</mo> <mi>d</mi> <mo>,</mo> <mrow> <mi mathvariant="fraktur">b</mi> </mrow> <mo mathvariant="fraktur" stretchy="false">)</mo> </mrow> <mrow> <mi>i</mi> </mrow> </msubsup> <mo stretchy="false">(</mo> <mo>−</mo> <mo stretchy="false">)</mo> </math></EquationSource> </InlineEquation> based on <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\((d,\frak{b})\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mo stretchy="false">(</mo> <mi>d</mi> <mo>,</mo> <mrow> <mi mathvariant="fraktur">b</mi> </mrow> <mo mathvariant="fraktur" stretchy="false">)</mo> </math></EquationSource> </InlineEquation>. As results we will see that over a Noetherian ring the functors <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(\Gamma_{(d,\frak{b})}(-)\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <msub> <mi mathvariant="normal">Γ</mi> <mrow> <mo stretchy="false">(</mo> <mi>d</mi> <mo>,</mo> <mrow> <mi mathvariant="fraktur">b</mi> </mrow> <mo mathvariant="fraktur" stretchy="false">)</mo> </mrow> </msub> <mo stretchy="false">(</mo> <mo>−</mo> <mo stretchy="false">)</mo> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(T_{(d,\frak{b})}(-)\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <msub> <mi>T</mi> <mrow> <mo stretchy="false">(</mo> <mi>d</mi> <mo>,</mo> <mrow> <mi mathvariant="fraktur">b</mi> </mrow> <mo mathvariant="fraktur" stretchy="false">)</mo> </mrow> </msub> <mo stretchy="false">(</mo> <mo>−</mo> <mo stretchy="false">)</mo> </math></EquationSource> </InlineEquation> preserve the <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\((d,\frak{b})\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mo stretchy="false">(</mo> <mi>d</mi> <mo>,</mo> <mrow> <mi mathvariant="fraktur">b</mi> </mrow> <mo mathvariant="fraktur" stretchy="false">)</mo> </math></EquationSource> </InlineEquation>-injectivity. Among other results, for a <InlineEquation ID="IEq11"> <EquationSource Format="TEX">\((d,\frak{b})\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mo stretchy="false">(</mo> <mi>d</mi> <mo>,</mo> <mrow> <mi mathvariant="fraktur">b</mi> </mrow> <mo mathvariant="fraktur" stretchy="false">)</mo> </math></EquationSource> </InlineEquation>-torsion free module <i>M</i>, we find a condition under which <InlineEquation ID="IEq12"> <EquationSource Format="TEX">\(T_{(d,\frak{b})}(M)\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <msub> <mi>T</mi> <mrow> <mo stretchy="false">(</mo> <mi>d</mi> <mo>,</mo> <mrow> <mi mathvariant="fraktur">b</mi> </mrow> <mo mathvariant="fraktur" stretchy="false">)</mo> </mrow> </msub> <mo stretchy="false">(</mo> <mi>M</mi> <mo stretchy="false">)</mo> </math></EquationSource> </InlineEquation> is injective.</p>

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\((d,\frak{b})\)-injectivity and some ideal transforms

  • Ahad Ghaffari,
  • Naser Zamani,
  • Mirsadegh Sayedsadeghi

摘要

Let R be a commutative ring with identity and M be an R-module. For a non-negative integer d and an ideal \(\frak{b}\) b of R, the concept of \((d,\frak{b})\) ( d , b ) -injectivity in the category of R-modules is defined. We characterize the \((d,\frak{b})\) ( d , b ) -injective hull of a module M as a submodule of E(M). Then we focus on the case when the ring R is Noetherian and see the connection with some modules caused by some ideal transform functor \(T_{(d,\frak{b})}(-)\) T ( d , b ) ( ) and some local cohomology functors \(H_{(d,\frak{b})}^{i}(-)\) H ( d , b ) i ( ) based on \((d,\frak{b})\) ( d , b ) . As results we will see that over a Noetherian ring the functors \(\Gamma_{(d,\frak{b})}(-)\) Γ ( d , b ) ( ) and \(T_{(d,\frak{b})}(-)\) T ( d , b ) ( ) preserve the \((d,\frak{b})\) ( d , b ) -injectivity. Among other results, for a \((d,\frak{b})\) ( d , b ) -torsion free module M, we find a condition under which \(T_{(d,\frak{b})}(M)\) T ( d , b ) ( M ) is injective.