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About a characterization of Dodds-Fremlin regarding positive compact operators - MaRDI portal

About a characterization of Dodds-Fremlin regarding positive compact operators (Q2839809)

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scientific article; zbMATH DE number 6187718
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About a characterization of Dodds-Fremlin regarding positive compact operators
scientific article; zbMATH DE number 6187718

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    12 July 2013
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    Banach lattices
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    AM-compact
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    operator
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    About a characterization of Dodds-Fremlin regarding positive compact operators (English)
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    Let \(E, F\) be Banach lattices and \(X\) a Banach space. A bounded operator \(T:E\rightarrow X\) is called AM-compact if it maps order intervals into relatively compact sets; an operator \( X\rightarrow E\) is called semicompact if for every \(\epsilon > 0\) there exists \(u\in E^+\) such that \(T(B_X) \subset [-u, u] + \epsilon B_E\), where \(B_E, B_X\) denote the closed unit balls of \(E\) and \(X\).NEWLINENEWLINEThe authors first give necessary conditions for a semicompact operator \(T:E\rightarrow F\) whose adjoint \(T'\) is AM-compact to be compact, and then they prove the following.NEWLINENEWLINETheorem. The following are equivalent:NEWLINENEWLINE1. Every positive operator \(T: E\rightarrow F\) is compact whenever it is AM-compact and \(T'\) is semicompact.NEWLINENEWLINE2. \(F\) is finite dimensional or \(E'\) has order continuous norm.
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