Results 1 to 10 of about 236 (32)

Compact perturbations of operators with property (t)

Open Mathematics, 2021
Let ℋ{\mathcal{ {\mathcal H} }} be an infinite dimensional complex Hilbert space and ℬ(ℋ){\mathcal{ {\mathcal B} }}\left({\mathcal{ {\mathcal H} }}) the algebra of all bounded linear operators on ℋ{\mathcal{ {\mathcal H} }}.
Yu Xinling, Shi Weijuan, Ji Guoxing
doaj   +1 more source

On hyponormality on a weighted annulus

Open Mathematics, 2021
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+ψ¯\varphi +\overline{\psi }, where φ\varphi and ψ\psi are ...
Sadraoui Houcine, Halouani Borhen, Garayev Mubariz T.   +2 more
doaj   +1 more source

Remarks on hyponormal Toeplitz operators with nonharmonic symbols

Open Mathematics, 2023
In this article, we present some necessary or sufficient conditions for the hyponormality of Toeplitz operator Tφ{T}_{\varphi } on the Bergman space A2(D){A}^{2}\left({\mathbb{D}}).
Kim Sumin, Lee Jongrak
doaj   +1 more source

Range-Kernel orthogonality and elementary operators on certain Banach spaces

Demonstratio Mathematica, 2021
The characterization of the points in Cp:1 ...
Bachir Ahmed, Segres Abdelkader, Sayyaf Nawal Ali, Ouarghi Khalid   +3 more
doaj   +1 more source

Range-kernel weak orthogonality of some elementary operators

Open Mathematics, 2021
We study the range-kernel weak orthogonality of certain elementary operators induced by non-normal operators, with respect to usual operator norm and the Von Newmann-Schatten pp-norm (1 ...
Bachir Ahmed, Segres Abdelkader, Sayyaf Nawal A.   +2 more
doaj   +1 more source

Normality and Quasinormality of Specific Bounded Product of Densely Defined Composition Operators in L2 Spaces

Concrete Operators, 2022
Let (X, 𝒜, μ) be a σ−finite measure space. A transformation ϕ : X → X is non-singular if μ ∘ ϕ−1 is absolutely continuous with respect with μ. For this non-singular transformation, the composition operator Cϕ: 𝒟(Cϕ) → L2(μ) is defined by Cϕf = f ∘ ϕ, f ∈
Zhou Hang
doaj   +1 more source

Berezin number inequalities for operators

Concrete Operators, 2019
The Berezin transform à of an operator A, acting on the reproducing kernel Hilbert space ℋ = ℋ (Ω) over some (non-empty) set Ω, is defined by Ã(λ) = 〉Aǩ λ, ǩ λ〈 (λ ∈ Ω), where k⌢λ=kλ‖kλ‖${\mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\frown ...
Bakherad Mojtaba, Garayev Mubariz T.
doaj   +1 more source

Product and factorization of hypo-EP operators

Special Matrices, 2018
In this article, we derive some necessary and sufficient conditions for the product of hypo-EP operators to be hypo-EP and we characterize hypo-EP operators through factorizations.
Johnson P. Sam, Vinoth A.
doaj   +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

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