<p>In this paper, we study the approximate minimizing property (AMp) for operators, a localized Bishop-Phelps-Bollobás type property with respect to the minimum norm. Given Banach spaces <i>X</i> and <i>Y</i> we define a new class <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="43036_2024_415_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="84" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathcal{A}\mathcal{M}(X,Y)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="script">A</mi> <mi mathvariant="script">M</mi> <mo stretchy="false">(</mo> <mi>X</mi> <mo>,</mo> <mi>Y</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> of bounded linear operators from <i>X</i> to <i>Y</i> for which the pair (<i>X</i>,&#xa0;<i>Y</i>) satisfies the AMp. We provide a necessary and sufficient condition for non-injective operators from <i>X</i> to <i>Y</i> to be in the class <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="43036_2024_415_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="84" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathcal{A}\mathcal{M}(X,Y)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="script">A</mi> <mi mathvariant="script">M</mi> <mo stretchy="false">(</mo> <mi>X</mi> <mo>,</mo> <mi>Y</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>. We also prove that <i>X</i> is finite dimensional if and only if for every Banach space <i>Y</i>, (<i>X</i>,&#xa0;<i>Y</i>) has the AMp for all minimum norm attaining operators from <i>X</i> to <i>Y</i> if and only if for every Banach space <i>Y</i>, (<i>Y</i>,&#xa0;<i>X</i>) has the AMp for all minimum norm attaining operators from <i>Y</i> to <i>X</i>. We also study the AMp with respect to Crawford number called AMp-<i>c</i> for operators.</p>

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Localized Bishop-Phelps-Bollobás type properties for minimum norm and Crawford number attaining operators

  • Uday Shankar Chakraborty

摘要

In this paper, we study the approximate minimizing property (AMp) for operators, a localized Bishop-Phelps-Bollobás type property with respect to the minimum norm. Given Banach spaces X and Y we define a new class \(\mathcal{A}\mathcal{M}(X,Y)\) A M ( X , Y ) of bounded linear operators from X to Y for which the pair (XY) satisfies the AMp. We provide a necessary and sufficient condition for non-injective operators from X to Y to be in the class \(\mathcal{A}\mathcal{M}(X,Y)\) A M ( X , Y ) . We also prove that X is finite dimensional if and only if for every Banach space Y, (XY) has the AMp for all minimum norm attaining operators from X to Y if and only if for every Banach space Y, (YX) has the AMp for all minimum norm attaining operators from Y to X. We also study the AMp with respect to Crawford number called AMp-c for operators.