Absolute continuity and hyponormal operators.
Putnam, C.R. (1981)
International Journal of Mathematics and Mathematical Sciences
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Putnam, C.R. (1981)
International Journal of Mathematics and Mathematical Sciences
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Aluthge, Ariyadasa, Wang, Derming (1999)
Journal of Inequalities and Applications [electronic only]
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Schôichi Ôta, Franciszek Hugon Szafraniec (2004)
Studia Mathematica
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The paper concerns operators of deformed structure like q-normal and q-hyponormal operators with the deformation parameter q being a positive number different from 1. In particular, an example of a q-hyponormal operator with empty spectrum is given, and q-hyponormality is characterized in terms of some operator inequalities.
C. Benhida, E. H. Zerouali (2009)
Studia Mathematica
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Let R and S be two operators on a Hilbert space. We discuss the link between the subscalarity of RS and SR. As an application, we show that backward Aluthge iterates of hyponormal operators and p-quasihyponormal operators are subscalar.
J. Janas (1994)
Studia Mathematica
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The paper deals mostly with spectral properties of unbounded hyponormal operators. Some nontrivial examples of such operators are given.
William F. Donoghue (1963)
Publications Mathématiques de l'IHÉS
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Mohammed Hichem Mortad (2011)
Colloquium Mathematicae
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We present a new approach to the question of when the commutativity of operator exponentials implies that of the operators. This is proved in the setting of bounded normal operators on a complex Hilbert space. The proofs are based on some results on similarities by Berberian and Embry as well as the celebrated Fuglede theorem.
Bernard Morrel, Paul Muhly (1974)
Studia Mathematica
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Nathan S. Feldman (2002)
Studia Mathematica
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We show that there are linear operators on Hilbert space that have n-dimensional subspaces with dense orbit, but no (n-1)-dimensional subspaces with dense orbit. This leads to a new class of operators, called the n-supercyclic operators. We show that many cohyponormal operators are n-supercyclic. Furthermore, we prove that for an n-supercyclic operator, there are n circles centered at the origin such that every component of the spectrum must intersect one of these circles.
Che-Kao Fong (1979)
Studia Mathematica
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Mecheri, Salah (2005)
Revista Colombiana de Matemáticas
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Duggal, B.P. (2005)
International Journal of Mathematics and Mathematical Sciences
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Muneo Chō, Tadasi Huruya, Masuo Itoh (1998)
Studia Mathematica
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The purpose of this paper is to give singular integral models for p-hyponormal operators and apply them to the Riemann-Hilbert problem.
S. M. Patel (1983)
Publications de l'Institut Mathématique
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