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Biquasitriangularity and spectral continuity

Published online by Cambridge University Press:  18 May 2009

Ridgley Lange
Ridgley Lange
Affiliation:
Central Michigan University, Mount Pleasant, Michigan 48859
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In [6] Conway and Morrell characterized those operators on Hilbert space that are points of continuity of the spectrum. They also gave necessary and sufficient conditions that a biquasitriangular operator be a point of spectral continuity. Our point of view in this note is slightly different. Given a point T of spectral continuity, we ask what can then be inferred. Several of our results deal with invariant subspaces. We also give some conditions characterizing a biquasitriangular point of spectral continuity (Theorem 3). One of these is that the operator and its adjoint both have the single-valued extension property.

Type
Research Article
Information
Glasgow Mathematical Journal , Volume 26 , Issue 2 , July 1985 , pp. 177 - 180
Copyright
Copyright © Glasgow Mathematical Journal Trust 1985

References

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