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Closures of direct sums of classes of operators


Author: Don Hadwin
Journal: Proc. Amer. Math. Soc. 121 (1994), 697-701
MSC: Primary 47D99; Secondary 46H15, 47A15, 47A20
DOI: https://doi.org/10.1090/S0002-9939-1994-1209423-1
MathSciNet review: 1209423
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Abstract: We prove that certain classes of Hilbert space operators that are direct sums of operators in specified classes are closed under sequential $ \ast $-strong limits. One such example is the class of operators that are direct sums of operators that are either subnormal or have imaginary parts with spectrum contained in $ [0,1] \cup [2,3]$.


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Additional Information

DOI: https://doi.org/10.1090/S0002-9939-1994-1209423-1
Article copyright: © Copyright 1994 American Mathematical Society

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