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On the unitary
invariance of the numerical radius
Ivan Filippenko and Marvin David Marcus |
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Vol. 75 (1978), No. 2, 383–395
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Abstract |
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A characterization is obtained of scalar multiples of unitary matrices in terms of the unitary invariance of a generalized numerical radius. The method of proof involves some rather delicate combinatorial considerations. |
Mathematical Subject Classification 2000
Primary: 15A15
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Milestones
Received: 5 May 1977
Published: 1 April 1978
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Authors |
| Ivan Filippenko | |
| Marvin David Marcus | |
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