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The spectra of subnormal operators


Author: C. R. Putnam
Journal: Proc. Amer. Math. Soc. 28 (1971), 473-477
MSC: Primary 47.40
DOI: https://doi.org/10.1090/S0002-9939-1971-0275215-8
MathSciNet review: 0275215
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Abstract: It is shown that a subnormal operator having its spectrum on a simple closed curve is necessarily normal, and that the corresponding assertion with ``subnormal'' replaced by ``hyponormal'' is in general false.


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Additional Information

DOI: https://doi.org/10.1090/S0002-9939-1971-0275215-8
Keywords: Spectra of hyponormal operators, spectra of subnormal operators, measure of spectrum
Article copyright: © Copyright 1971 American Mathematical Society

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