Results 61 to 70 of about 137 (130)

Powers of -Hyponormal operators

Journal of Inequalities and Applications, 1999
Applying Furuta's and Hansen's inequalities, it is shown that if is a -hyponormal operator, then is -hyponormal. Applications are obtained.
Wang Derming, Aluthge Ariyadasa
doaj  

On Unitary Quasi-Square Equivalence and Related Classes of Operators

Wasit Journal for Pure Sciences
This paper introduces and systematically investigates the notion of unitary quasi-square equivalence for bounded linear operators on Hilbert spaces.
Victor Wanjala
doaj   +1 more source

On intertwining and w-hyponormal operators [PDF]

Opuscula Mathematica, 2005
Given \(A, B\in B(H)\), the algebra of operators on a Hilbert Space \(H\), define \(\delta_{A,B}: B(H) \to B(H)\) and \(\Delta_{A,B}: B(H) \to B(H)\) by \(\delta_{A,B}(X)=AX-XB\) and \(\Delta_{A,B}(X)=AXB-X\). In this note, our task is a twofold one.
M. O. Otieno
doaj  

Generalizations of the results on powers of -hyponormal operators

Journal of Inequalities and Applications, 2001
Recently, as a nice application of Furuta inequality, Aluthge and Wang (J. Inequal. Appl., 3 (1999), 279–284) showed that "if is a -hyponormal operator for , then is -hyponormal for any positive integer ," and Furuta and Yanagida (Scientiae ...
Ito Masatoshi
doaj  

Extensions of the results on powers of -hyponormal and -hyponormal operators

Journal of Inequalities and Applications, 2006
Firstly, we will show the following extension of the results on powers of -hyponormal and -hyponormal operators: let and be positive integers, if is -hyponormal for , then: (i) in case , and hold, (ii) in case , and hold.
Yang Changsen, Yuan Jiangtao
doaj  

A note on -hyponormal operators

Journal of Inequalities and Applications, 2002
Let be a -hyponormal operator with the polar decomposition . In this paper, we show the following: (1) If is normal, then is normal. (2) If , then is also -hyponormal. (3) There exists a -hyponormal operator such that and .
Huruya Tadasi, Kim Young Ok, Chō Muneo   +2 more
doaj  

M-hyponormality in several variables operator theory

Journal of Inequalities and Applications
In recent years, the study of bounded linear operators in several variables has received great interest from many authors, including the second author’s previous contributions.
Ohud Bulayhan Almutairi, Sid Ahmed Ould Ahmed Mahmoud   +1 more
doaj   +1 more source

On powers of -hyponormal and log-hyponormal operators

Journal of Inequalities and Applications, 2000
A bounded linear operator on a Hilbert space is said to be -hyponormal for if , and is said to be log-hyponormal if is invertible and . Firstly, we shall show the following extension of our previous result: If is -hyponormal for , then and hold ...
Furuta Takayuki, Yanagida Masahiro
doaj  

Jointly $\mathcal{A}$-Paranormal Tuples of Operators in Semi-Hilbertian Spaces

Mathematics
This paper introduces the concept of jointly A-paranormal operator tuples acting on semi-Hilbertian spaces. We establish foundational operator inequalities and structural properties governing this new class.
Reem K. Alhefthi
doaj   +1 more source

Quasisimilarity of Hyponormal and Subdecomposable Operators

Journal of Functional Analysis, 1993
For separable complex Hilbert spaces \({\mathcal H}_ 0\) and \(\mathcal H\) let \({\mathcal L}({\mathcal H}_ 0)\) and \({\mathcal L}({\mathcal H})\) be the corresponding spaces of bounded linear operators. If \(T\in {\mathcal L}({\mathcal H}_ 0)\) is an operator without eigenvalues, \(S\in {\mathcal L}({\mathcal H})\) is a subdecomposable operator (i.e.
openaire   +2 more sources