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Conditions for a composition operator on the Hardy space of the disk to have closed range or be similar to an isometry are well known. We provide such conditions for composition operators on the Hardy space of the upper half-plane. We also…

Functional Analysis · Mathematics 2012-05-08 Hari Bercovici , Dan Timotin

We study when multiplication by a weight can turn a non-compact composition operator on H 2 into a compact operator, and when it can be in Schatten classes. The q-summing case in H p is considered. We also study when this multiplication can…

Functional Analysis · Mathematics 2019-04-16 Pascal Lefèvre , Daniel Li , Hervé Queffélec , Luis Rodriguez-Piazza

In this paper, we first characterize the polar decomposition of unbounded weighted composition operator pairs $\textbf{C}_{\phi,\omega}$ in an $L^2$-space. Based on this characterization, we introduce the $\lambda$-spherical mean transform…

Functional Analysis · Mathematics 2025-10-21 Jing-Bin Zhou , Shihai Yang

Here we consider when the difference of two composition operators is compact on the weighted Dirichlet spaces $\mathcal{D}_\alpha$. Specifically we study differences of composition operators on the Dirichlet space $\mathcal{D}$ and $S^2$,…

Functional Analysis · Mathematics 2022-07-27 Robert F. Allen , Katherine Heller , Matthew A. Pons

We prove that the norm of a weighted composition operator on the Hardy space H^2 of the disk is controlled by the norm of the weight function in the de Branges-Rovnyak space associated to the symbol of the composition operator. As a…

Functional Analysis · Mathematics 2007-07-24 Michael T. Jury

A criterion for subnormality of unbounded composition operators in L2-spaces, written in terms of measurable families of probability measures satisfying the so-called consistency condition, is established. It becomes a new characterization…

Functional Analysis · Mathematics 2013-03-27 Piotr Budzynski , Zenon Jan Jablonski , Il Bong Jung , Jan Stochel

We establish necessary and sufficient conditions for the boundedness and compactness of weighted composition operators acting on weighted Dirichlet spaces and determine the spectrum of a certain class of such operators. Our results extend…

Functional Analysis · Mathematics 2026-02-10 Anirban Sen

In this paper, we study the basic properties such as boundedness and compactness of composition operators on discrete analogue of generalized Hardy space defined on a homogeneous rooted tree. Also, we compute the operator norm of…

Functional Analysis · Mathematics 2016-10-03 Perumal Muthukumar , Saminathan Ponnusamy

Let $\phi(z)=(\phi_1(z),...,\phi_n(z))$ be a holomorphic self-map of $B$ and $\psi(z)$ a holomorphic function on $B$, where $B$ is the unit ball of ${\Bbbb C}^n$. Let $0<p,s<+\infty, -n-1<q<+\infty, q+s>-1$ and $\alpha\geq 0,$ this paper…

Complex Variables · Mathematics 2013-12-03 Zehua Zhou , Renyu Chen

In this work, we prove that weak compactness of composition operator on $H^{1}(U^{n})$ coincides with its compactness. We also characterize bounded and compact composition operators on $H^{1}(U^{n}).$\

Complex Variables · Mathematics 2007-05-23 Turgay Bayraktar

Let {\phi} be an analytic self-map of D and be an analytic operator-valued function on D, where D is the unit disk. We provide necessary and sufficient conditions for the boundedness and compactness of weighted composition operators…

Functional Analysis · Mathematics 2016-04-22 Kobra Esmaeili

We investigate the relationship between the complex symmetry of composition operators $C_{\phi}f=f\circ \phi$ induced on the classical Hardy space $H^2(\mathbb{D})$ by an analytic self-map $\phi$ of the open unit disk $\mathbb{D}$ and its…

Functional Analysis · Mathematics 2020-09-17 S. Waleed Noor , Osmar R. Severiano

In this paper, we present the current results in the study of weighted composition operators on the Bloch space of bounded homogeneous domains in $\mathbb{C}^n$ with particular emphasis on the issues of boundedness and compactness. We also…

Complex Variables · Mathematics 2022-07-26 Robert F. Allen , Flavia Colonna

Bounded and unbounded weighted composition operators on $L^2$ spaces over $\sigma$-finite measure spaces are investigated. A variety of questions related to seminormality of such operators are discussed.

Functional Analysis · Mathematics 2017-02-07 Piotr Budzyński , Zenon Jan Jabłoński , Il Bong Jung , Jan Stochel

We construct an analytic self-map $\Phi$ of the bidisk ${\mathbb D}^2$ whose image touches the distinguished boundary, but whose approximation numbers of the associated composition operator on $H^2 ({\mathbb D}^2)$ are small in the sense…

Functional Analysis · Mathematics 2019-01-23 Daniel Li , Hervé Queffélec , Luis Rodríguez-Piazza

In this thesis, we establish a necessary and sufficient condition for a weighted composition operator to commute with a self-adjoint weighted composition operator on the Fock space, then obtain a sufficient condition for these commuting…

Functional Analysis · Mathematics 2024-03-26 Rui Hu

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

We consider the invariant subspace of composition operators on Hardy space $H^p$ where the composition operators corresponding to a function $\varphi$ that is a holomorphic self-map of $\mathbb D$. Firstly, we discuss composition operators…

Functional Analysis · Mathematics 2021-01-21 Tianyu Bai , Junming Liu

A weighted mean matrix whose weight sequence is linear with positive coefficients is shown to be a posinormal operator on $\ell^2$. This operator is also shown to be coposinormal, so it and its adjoint have the same null space and the same…

Functional Analysis · Mathematics 2019-01-18 H. C. Rhaly

We characterize the convex-cyclic weighted composition operators $W_{(u,\psi)}$ and their adjoints on the Fock space in terms of the derivative powers of $ \psi$ and the location of the eigenvalues of the operators on the complex plane.…

Functional Analysis · Mathematics 2021-12-13 Tesfa Mengestie
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