Results 1 to 10 of about 435 (74)

Bishop's property (β), hypercyclicity and hyperinvariant subspaces

, 2014
The question whether every operator on H has an hyperinvariant subspace is one of the most difficult problems in operator theory. The purpose of this paper is to make a beginning on the hyperinvariant subspace problems for another class of operators ...
S. Mécheri
semanticscholar   +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  

Complex symmetric weighted composition Lambert type operators on L^2(Σ)

, 2018
In this paper we obtain the polar decomposition and the Aluthge transform of a weighted composition Lambert type operator MwEMuCφ on L2(Σ) . In addition, we study the complex symmetry of these types of operators induced by triple (w,u,φ) .
M. Jabbarzadeh, M. Moradi
semanticscholar   +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

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

Hyponormal Toeplitz operators with polynomial symbols on weighted Bergman spaces

, 2014
In this note we consider the hyponormality of Toeplitz operators Tφ on weighted Bergman space Aα2(D) with symbol in the class of functions f+g¯ with polynomials f and g.MSC:47B20, 47B35.
I. Hwang, Jongrak Lee, S. W. Park
semanticscholar   +1 more source

A note on k-paranormal operators

, 2010
It is still unknown whether the inverse of an invertible k -paranormal operator is normaloid, and so whether a k -paranormal operator is totally hereditarily normaloid.
C. Kubrusly, B. Duggal
semanticscholar   +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  

Bishop's property (β) for paranormal operators

, 2009
For an operator T on a separable complex Hilbert space H , we say that T has Bishop’s property (β) if for any open subset D ⊂ C and any sequence of analytic functions fn : D →H such as ‖(T −z) fn(z)‖→ 0 as n→∞ uniformly on every compact subset K ⊂D ...
A. Uchiyama, K. Tanahashi
semanticscholar   +1 more source