On the normality of operators.
Mecheri, Salah (2005)
Revista Colombiana de Matemáticas
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Mecheri, Salah (2005)
Revista Colombiana de Matemáticas
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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.
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.
Galakhov, E. (1997)
Memoirs on Differential Equations and Mathematical Physics
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Ryotaro Sato (1976)
Colloquium Mathematicae
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Ryotaro Sato (1976)
Colloquium Mathematicae
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Beatriz Margolis (1972)
Annales Polonici Mathematici
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Miroslav Sova (1982)
Časopis pro pěstování matematiky
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S.C. Arora, Ramesh Kumar (1981)
Publications de l'Institut Mathématique
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Abdelkader Benali, Mohammed Hichem Mortad (2014)
Bulletin of the Polish Academy of Sciences. Mathematics
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We are mainly concerned with the result of Kaplansky on the composition of two normal operators in the case in which at least one of the operators is unbounded.
Chun Guang Li, Ting Ting Zhou (2014)
Studia Mathematica
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A bounded linear operator T acting on a Hilbert space is said to be polaroid if each isolated point in the spectrum is a pole of the resolvent of T. There are several generalizations of the polaroid property. We investigate compact perturbations of polaroid type operators. We prove that, given an operator T and ε > 0, there exists a compact operator K with ||K|| < ε such that T + K is polaroid. Moreover, we characterize those operators for which a certain polaroid type property...
Messirdi, Bekkai, Mortad, Mohammed Hichem (2008)
Banach Journal of Mathematical Analysis [electronic only]
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Sever Silvestru Dragomir (2017)
Concrete Operators
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Some trace inequalities of Shisha-Mond type for operators in Hilbert spaces are provided. Applications in connection to Grüss inequality and for convex functions of selfadjoint operators are also given.
M. R. Dostanić (1989)
Matematički Vesnik
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John B. Conway, Gabriel Prǎjiturǎ (2005)
Studia Mathematica
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For a scalar λ, two operators T and S are said to λ-commute if TS = λST. In this note we explore the pervasiveness of the operators that λ-commute with a compact operator by characterizing the closure and the interior of the set of operators with this property.