On an analogue of a theorem by Astala and Tylli

被引:0
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作者
Alexei Karlovich
Eugene Shargorodsky
机构
[1] Universidade Nova de Lisboa,Centro de Matemática e Aplicações, Departamento de Matemática, Faculdade de Ciências e Tecnologia
[2] King’s College London,Department of Mathematics
[3] Technische Universität Dresden,Fakultät Mathematik
来源
Archiv der Mathematik | 2022年 / 118卷
关键词
Essential norm; Measures of noncompactness; Bounded compact approximation property; Dual compact approximation property; Primary 46B28; Secondary 46B50; 47B07; 47H08;
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摘要
Let ‖A‖e\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Vert A\Vert _{\mathrm {e}}$$\end{document} be the essential norm of an operator A and ‖A‖m\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Vert A\Vert _m$$\end{document} be the infimum of the norms of restrictions of A to the subspaces of finite codimension. We show that if ‖A‖e<M‖A‖m\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Vert A\Vert _{\mathrm {e}}<M\Vert A\Vert _m$$\end{document} holds for every bounded noncompact operator A from a Banach space X to every Banach space Y, then the space X has the dual compact approximation property. This is an analogue of a result by Astala and Tylli (J Funct Anal 70(2):388–401, 1987) concerning the Hausdorff measure of noncompactness and the bounded compact approximation property.
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页码:73 / 77
页数:4
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