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We prove the subnormality of an operator-weighted composition operator whose symbol is a transformation of a discrete measure space and weights are multiplication operators in $L^2$-spaces under the assumption of existence of a family of…

Functional Analysis · Mathematics 2018-09-06 Piotr Budzynski , Piotr Dymek , Artur Planeta

The questions of dense definiteness and boundedness of composition operators in $L^2$-spaces are studied by means of inductive limits of operators. Methods based on projective systems of measure spaces and inductive limits of $L^2$-spaces…

Functional Analysis · Mathematics 2018-09-06 Piotr Budzynski , Artur Planeta

In this paper we define $\lambda$-hyponormal operators on an infinite dimensional Hilbert space $\mathcal{H}$ and find a class of $\lambda$-hyponormal operators that can not be hypercyclic. Also, we study closedness of range and…

Functional Analysis · Mathematics 2025-08-07 Y. Estaremi , M. S. Al Ghafri , and S. Shamsigamchi

Let $T$ be a bounded linear operator on a Hilbert space. Then the Aluthge transform $\Delta T$ and the sequence $(\Delta^nT)$ of Aluthge iterates of $T$ are defined by \begin{align*} \Delta…

Functional Analysis · Mathematics 2026-05-05 Neeru Bala

Let $T\in B(H)$ be a bounded linear operator on a Hilbert space $H$, let $T = V|T|$ be its polar decomposition of $T$ and let $\lambda\in [0,1]$. The $\lambda$-Aluthge transform $\Delta_{\lambda}(T)$ and the mean transforms $M(T)$ are…

Functional Analysis · Mathematics 2022-03-30 Fadil Chabbabi , Maëva Ostermann

In this paper, we study weighted composition operators on the Fock space. We show that a weighted composition operator is cohyponorma if and only if it is normal. Moreover, we give a complete characterization of closed range weighted…

Functional Analysis · Mathematics 2018-09-14 Mahsa Fatehi

In this note, we verify that the bounded shadowing property and quasi-hyperbolicity of bounded linear operators on Hilbert spaces are preserved under Aluthge transforms.

Functional Analysis · Mathematics 2022-09-19 Linh Tran

We prove, by use of inductive techniques, that assorted unbounded composition operators in $L^2$-spaces with matrical symbols are cosubnormal.

Functional Analysis · Mathematics 2018-09-06 Piotr Budzynski , Piotr Dymek , Artur Planeta

In this note unbounded hyperexpansive weighted composition operators are investigated. AS a consequence unbounded hyperexpansive multiplication and composition operators are characterized.

Functional Analysis · Mathematics 2014-02-21 Yousef Estaremi

This paper aims to study the boundedness and compactness of composition operators from model spaces to the Hardy Hilbert spaces in the upper half-plane. Consequently, we investigate the boundedness and compactness of composition operators…

Functional Analysis · Mathematics 2026-05-13 Bharti Garg , Subhankar Mahapatra , Santanu Sarkar

We consider weighted composition operators, that is operators of the type $g \mapsto w \cdot g \circ f$, acting on spaces of Lipschitz functions. Bounded weighted composition operators, as well as some compact weighted composition…

Functional Analysis · Mathematics 2023-04-25 Arafat Abbar , Clément Coine , Colin Petitjean

The aim of this article is to detect the ascent and descent of weighted composition operators on Lorentz spaces. We investigate the conditions on the measurable transformation $T$ and the complex-valued measurable function $u$ defined on…

Functional Analysis · Mathematics 2024-04-26 Gopal Datt , Daljeet Singh Bajaj

In this paper we characterize $m$-isometric and quasi-$m$-isometric weighted composition operators on the Hilbert space $L^2(\mu)$. Also, we find that normal-$m$-isometry and normal quasi-$m$-isometry weighted composition operators have…

Functional Analysis · Mathematics 2025-09-25 M. S. Al Ghafri , Y. Estaremi , M. Z. Gashti

We introduce two natural notions of multivariable Aluthge transforms (toral and spherical), and study their basic properties. In the case of 2-variable weighted shifts, we first prove that the toral Aluthge transform does not preserve…

Functional Analysis · Mathematics 2018-12-11 Raul E. Curto , Jasang Yoon

Composition operators with analytic symbols on some reproducing kernel Hilbert spaces of entire functions on a complex Hilbert space are studied. The questions of their boundedness, seminormality and positivity are investigated. It is…

Functional Analysis · Mathematics 2016-10-17 Jan Stochel , Jerzy B. Stochel

We study weighted composition operators acting between Fock spaces. The following results are obtained: (1) Criteria for the boundedness and compactness; (2) Characterizations of compact differences and essential norm; (3) Complete…

Complex Variables · Mathematics 2017-04-13 Pham Trong Tien , Le Hai Khoi

In this paper we consider unbounded weighted conditional type operators on the space Lp, we give some conditions under which they are densely defined and we obtain a dense subset of the domain. Also, we get that a WCT operator is continuous…

Functional Analysis · Mathematics 2015-12-25 Yousef Estaremi

The concepts of weighted numerical radius has been defined in recent times. In this article, we obtain several upper bound for weighted numerical radius of operators and $2 \times 2$ operator matrices which generalize and improves some well…

Functional Analysis · Mathematics 2023-02-24 Raj Kumar Nayak

In the paper, we investigate weighted composition operators on Bergman spaces of a half-plane. We characterize weighted composition operators which are hermitian and those which are complex symmetric with respect to a family of…

Functional Analysis · Mathematics 2021-11-30 Pham Viet Hai , Osmar R. Severiano

We extend a classical result of Caughran/Schwartz and another recent result of Gunatillake by showing that if D is a bounded, convex domain in n-dimensional complex space, m is a holomorphic function on D and bounded away from zero toward…

Functional Analysis · Mathematics 2007-05-23 Dana D. Clahane