Results 21 to 30 of about 253 (51)

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

Hyponormality on a weighted Bergman space of an annulus with a general harmonic symbol

Open Mathematics
In this work we consider the hyponormality of Toeplitz operators on the Bergman space of the annulus with a logarithmic weight. We give necessary conditions when the symbol is of the form φ+ψ̄ $\varphi +\bar{\psi }$ where both φ and ψ are analytic on ...
Sadraoui Houcine, Halouani Borhen
doaj   +1 more source

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  

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  

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

Hausdorff moment sequences induced by rational functions

, 2019
We study the Hausdorff moment problem for a class of sequences, namely $(r(n))_{n\in\mathbb Z_+},$ where $r$ is a rational function in the complex plane. We obtain a necessary condition for such sequence to be a Hausdorff moment sequence.
Reza, Md. Ramiz, Zhang, Genkai
core   +1 more source

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

Operators commuting with complex symmetric weighted composition operators on H 2

Concrete Operators
In this article, we initially study when an anti-linear Toeplitz operator is in the commutant of a composition operator. Primarily, we investigate weighted composition operators Wg,ψ{W}_{g,\psi } commuting with complex symmetric weighted composition ...
Bhuia Sudip Ranjan
doaj   +1 more source

An Analytic Model for left invertible Weighted Translation Semigroups

, 2018
M. Embry and A. Lambert initiated the study of a semigroup of operators $\{S_t\}$ indexed by a non-negative real number $t$ and termed it as weighted translation semigroup. The operators $S_t$ are defined on $L^2(\mathbb R_+)$ by using a weight function.
Phatak, Geetanjali M., Sholapurkar, V. M.   +1 more
core