<p>We study copies of the classical sequence spaces <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(c_0\)</EquationSource> </InlineEquation> and <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(\ell _\infty \)</EquationSource> </InlineEquation> in spaces of <InlineEquation ID="IEq11"> <EquationSource Format="TEX">\(w^*\)</EquationSource> </InlineEquation>-<InlineEquation ID="IEq11111"> <EquationSource Format="TEX">\(w\)</EquationSource> </InlineEquation> continuous symmetric <i>n</i>-linear mappings. More precisely, we consider the Banach space <InlineEquation ID="IEq12"> <EquationSource Format="TEX">\(\mathcal {L}_{w^*s}(^n X^*, Y)\)</EquationSource> </InlineEquation> of all <InlineEquation ID="IEq13"> <EquationSource Format="TEX">\(w^*\)</EquationSource> </InlineEquation>-<InlineEquation ID="IEq11112"> <EquationSource Format="TEX">\(w\)</EquationSource> </InlineEquation> continuous symmetric <i>n</i>-linear mappings from <InlineEquation ID="IEq14"> <EquationSource Format="TEX">\(X^*\)</EquationSource> </InlineEquation> into <i>Y</i>, together with its closed subspace <InlineEquation ID="IEq15"> <EquationSource Format="TEX">\(\mathcal {K}_{w^*s}(^nX^*,Y)\)</EquationSource> </InlineEquation> consisting of compact operators. We prove that <InlineEquation ID="IEq16"> <EquationSource Format="TEX">\(\ell _\infty \)</EquationSource> </InlineEquation> embeds in <InlineEquation ID="IEq17"> <EquationSource Format="TEX">\(\mathcal {K}_{w^*s}(^nX^*,Y)\)</EquationSource> </InlineEquation> if and only if <InlineEquation ID="IEq18"> <EquationSource Format="TEX">\(\ell _\infty \)</EquationSource> </InlineEquation> embeds into either <i>X</i> or <i>Y</i>. As an application of this, we prove that if <InlineEquation ID="IEq19"> <EquationSource Format="TEX">\(c_{0}\)</EquationSource> </InlineEquation> embeds in <InlineEquation ID="IEq20"> <EquationSource Format="TEX">\(K_{w^*s}(^nX^*,Y)\)</EquationSource> </InlineEquation>, then <InlineEquation ID="IEq21"> <EquationSource Format="TEX">\(\mathcal {K}_{w^*s}(^nX^*,Y)=\mathcal {L}_{w^*s}(^n X^*, Y)\)</EquationSource> </InlineEquation> if and only if only one of the following statements is true: <OrderedList> <ListItem> <ItemNumber>(1)</ItemNumber> <ItemContent> <p><InlineEquation ID="IEq22"> <EquationSource Format="TEX">\(c_{0}\)</EquationSource> </InlineEquation> embeds in <i>Y</i> and <i>X</i> has the Schur property,</p> </ItemContent> </ListItem> <ListItem> <ItemNumber>(2)</ItemNumber> <ItemContent> <p><InlineEquation ID="IEq23"> <EquationSource Format="TEX">\(c_{0}\)</EquationSource> </InlineEquation> embeds in <i>X</i> and <i>Y</i> has the Schur property.</p> </ItemContent> </ListItem> </OrderedList></p>

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Copies of \(c_0\) and \(\ell _\infty \) in Banach spaces of \(w^*\)-\(w\)-continuous symmetric multilinear maps

  • Michael A. Rincón-Villamizar,
  • Sergio A. Pérez,
  • Diego J. Reyes-Rojas

摘要

We study copies of the classical sequence spaces \(c_0\) and \(\ell _\infty \) in spaces of \(w^*\) - \(w\) continuous symmetric n-linear mappings. More precisely, we consider the Banach space \(\mathcal {L}_{w^*s}(^n X^*, Y)\) of all \(w^*\) - \(w\) continuous symmetric n-linear mappings from \(X^*\) into Y, together with its closed subspace \(\mathcal {K}_{w^*s}(^nX^*,Y)\) consisting of compact operators. We prove that \(\ell _\infty \) embeds in \(\mathcal {K}_{w^*s}(^nX^*,Y)\) if and only if \(\ell _\infty \) embeds into either X or Y. As an application of this, we prove that if \(c_{0}\) embeds in \(K_{w^*s}(^nX^*,Y)\) , then \(\mathcal {K}_{w^*s}(^nX^*,Y)=\mathcal {L}_{w^*s}(^n X^*, Y)\) if and only if only one of the following statements is true: (1)

\(c_{0}\) embeds in Y and X has the Schur property,

(2)

\(c_{0}\) embeds in X and Y has the Schur property.