Norm for sums of two basic elementary operators (Q1935998)
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scientific article; zbMATH DE number 6137713
| Language | Label | Description | Also known as |
|---|---|---|---|
| English | Norm for sums of two basic elementary operators |
scientific article; zbMATH DE number 6137713 |
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Norm for sums of two basic elementary operators (English)
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21 February 2013
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The basic elementary operator \(M_{A,B}\) is defined on \(B(X)\) by \(M_{A,B}(Z) = AZB\). In this paper, the authors prove several estimates for the norm of the elementary operator \(M_{A,B} + M_{C,D}\). They also give some conditions, expressed in terms of the numerical range, under which the operator \(M_{A,B} + M_{C,D}\) attains its optimal value \(\|A\|\|B\| + \|C\|\|D\|\).
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elementary operators
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numerical range
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norm
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