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Boundary points of
joint numerical ranges
Muneo Chō and Makoto Takaguchi |
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Vol. 95 (1981), No. 1, 27–35
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Abstract |
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In this paper it is shown that the conical points of the joint numerical range belong to the joint spectrum. Moreover, we discuss the bare points and extreme points of the joint numerical ranges for the n-tuples of commuting normal operators and Toeplitz operators. |
Mathematical Subject Classification 2000
Primary: 47A12
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Milestones
Received: 6 August 1979
Revised: 12 March 1980
Published: 1 July 1981
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Authors |
| Muneo Chō | |
| Makoto Takaguchi | |
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