Continuous versions of an inequality due to Hoffman and Wielandt (Q1086803)

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scientific article; zbMATH DE number 3985959
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Continuous versions of an inequality due to Hoffman and Wielandt
scientific article; zbMATH DE number 3985959

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    Continuous versions of an inequality due to Hoffman and Wielandt (English)
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    1985
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    The author proves the following theorem: Let A and B be completely continuous operators on a Hilbert space H belonging to the Schmidt class with eigenvalues \(\{\alpha_ i\}\) and \(\{\beta_ i\}\) respectively, taking account of their multiplicities. If \(A\geq 0\), and B is normal with Re\((B)\geq 0\), then there exists a suitable numbering of the eigenvalues such that \[ \sum^{\infty}_{i=1}| \alpha_ i-\beta_ i|^ 2\leq \| A-B\|^ 2. \]
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    normal matrix
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    Hoffman-Wielandt inequality
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    completely continuous operators
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    Schmidt class
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