<p>In this paper we analyse when every element of <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="43037_2024_400_Article_IEq1.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="51" /> </InlineMediaObject> <EquationSource Format="TEX">\(X{\widehat{\otimes }}_\pi Y\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>X</mi> <msub> <mover accent="true"> <mo>⊗</mo> <mo stretchy="true">^</mo> </mover> <mi>π</mi> </msub> <mi>Y</mi> </mrow> </math></EquationSource> </InlineEquation> attains its projective norm. We prove that this is the case if <i>X</i> is the dual of a subspace of a predual of an <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="43037_2024_400_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="36" /> </InlineMediaObject> <EquationSource Format="TEX">\(\ell _1(I)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>ℓ</mi> <mn>1</mn> </msub> <mrow> <mo stretchy="false">(</mo> <mi>I</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> space and <i>Y</i> is 1-complemented in its bidual under approximation property assumptions. This result allows us to provide some new examples where <i>X</i> is a Lipschitz-free space. We also prove that the set of norm-attaining elements is dense in <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="43037_2024_400_Article_IEq1.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="51" /> </InlineMediaObject> <EquationSource Format="TEX">\(X{\widehat{\otimes }}_\pi Y\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>X</mi> <msub> <mover accent="true"> <mo>⊗</mo> <mo stretchy="true">^</mo> </mover> <mi>π</mi> </msub> <mi>Y</mi> </mrow> </math></EquationSource> </InlineEquation> if, for instance, <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="43037_2024_400_Article_IEq4.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="79" /> </InlineMediaObject> <EquationSource Format="TEX">\(X=L_1(\mu )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>X</mi> <mo>=</mo> <msub> <mi>L</mi> <mn>1</mn> </msub> <mrow> <mo stretchy="false">(</mo> <mi>μ</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> and <i>Y</i> is any Banach space, or if <i>X</i> has the metric <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="43037_2024_400_Article_IEq5.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="13" /> </InlineMediaObject> <EquationSource Format="TEX">\(\pi \)</EquationSource> <EquationSource Format="MATHML"><math> <mi>π</mi> </math></EquationSource> </InlineEquation>-property and <i>Y</i> is a dual space with the RNP.</p>

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Projective tensor products where every element is norm-attaining

  • Luis C. García-Lirola,
  • Juan Guerrero-Viu,
  • Abraham Rueda Zoca

摘要

In this paper we analyse when every element of \(X{\widehat{\otimes }}_\pi Y\) X ^ π Y attains its projective norm. We prove that this is the case if X is the dual of a subspace of a predual of an \(\ell _1(I)\) 1 ( I ) space and Y is 1-complemented in its bidual under approximation property assumptions. This result allows us to provide some new examples where X is a Lipschitz-free space. We also prove that the set of norm-attaining elements is dense in \(X{\widehat{\otimes }}_\pi Y\) X ^ π Y if, for instance, \(X=L_1(\mu )\) X = L 1 ( μ ) and Y is any Banach space, or if X has the metric \(\pi \) π -property and Y is a dual space with the RNP.