Results 21 to 30 of about 233 (33)

Cohyponormal operators with the single valued extension property

International Journal of Mathematics and Mathematical Sciences, Volume 9, Issue 4, Page 659-663, 1986., 1986
It is proved that in order to find a nontrivial hyperinvariant subspace for a cohyponormal operator it suffices to make the further assumption that the operator have the single‐valued extension property.
Ridgley Lange, Shengwang Wang
wiley   +1 more source

Absolute continuity and hyponormal operators

International Journal of Mathematics and Mathematical Sciences, Volume 4, Issue 2, Page 321-335, 1981., 1981
Let T be a completely hyponormal operator, with the rectangular representation T = A + iB, on a separable Hilbert space. If 0 is not an eigenvalue of T* then T also has a polar factorization T = UP, with U unitary. It is known that A, B and U are all absolutely continuous operators.
C. R. Putnam
wiley   +1 more source

Moments from their very truncations

, 2007
It is known that positive definiteness is not enough for the multidimensional moment problem to be solved. We would like throw in to the garden of existing in this matter so far results one more, a result which takes into considerations the utmost ...
Szafraniec, F. H.
core   +1 more source

The single equality $A^{*n}A^n = (A^*A)^n$ does not imply the quasinormality of weighted shifts on rootless directed trees

, 2015
It is proved that each bounded injective bilateral weighted shift $W$ satisfying the equality $W^{*n}W^{n}=(W^{*}W)^{n}$ for some integer $n\geq 2$ is quasinormal. For any integer $n\geq 2$, an example of a bounded non-quasinormal weighted shift $A$ on a
Pietrzycki, Paweł
core   +1 more source

Spectra of subnormal pairs [PDF]

, 2007
In this short note we present an example related to joint spectra of subnormal pairs of bounded operators. A counterexample to the equality between Taylor's spectrum and the closure of the defect spectrum is given. This example is related to the author's
Krzysztof Rudol
core  

Generalized Derivations and Norm Equality in Normed Ideals [PDF]

, 2011
2000 Mathematics Subject Classification: 47A10, 47A12, 47A30, 47B10, 47B20, 47B37, 47B47, 47D50.We compare the norm of a generalized derivation on a Hilbert space with the norm of its restrictions to Schatten norm ...
Barraa, Mohamed
core  

On ergodic operator means in Banach spaces

, 2015
We consider a large class of operator means and prove that a number of ergodic theorems, as well as growth estimates known for particular cases, continue to hold in the general context under fairly mild regularity conditions. The methods developed in the
Aleman, Alexandru, Suciu, Laurian
core   +1 more source

On intertwining and w-hyponormal operators [PDF]

, 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
core  

Some inequalities for $(\alpha, \beta)$-normal operators in Hilbert spaces

, 2008
An operator $T$ acting on a Hilbert space is called $(\alpha ,\beta)$-normal ($0\leq \alpha \leq 1\leq \beta $) if \begin{equation*} \alpha ^{2}T^{\ast }T\leq TT^{\ast}\leq \beta ^{2}T^{\ast}T.
Dragomir, Sever S., Moslehian, Mohammad Sal   +1 more
core  

Synthesis of active distributed RC networks [PDF]

Open-circuit transfer function of two-port network expressed as rational function with real ...
Fu, J. S., Fu, Y.
core   +1 more source