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In this paper we completely describe the numerical range of Toeplitz operators on weighted Bergman spaces with harmonic symbol. We also characterize the numerical range of weighted composition operators on weighted Bergman spaces and…

Functional Analysis · Mathematics 2025-02-06 Anirban Sen , Subhadip Halder , Riddhick Birbonshi , Kallol Paul

In this paper, we provide some sufficient conditions for the compactness of weighted composition operators on Dirichlet space. Furthermore, we characterize the numerical range of certain classes of weighted composition operators on…

Functional Analysis · Mathematics 2026-01-05 Subhadip Halder , Sweta Mukherjee , Riddhick Birbonshi

In this paper, we consider the sum of weighted composition operator $C_{\psi_{0},\varphi_{0}}$ and the weighted composition--differentiation operator $D_{\psi_{n},\varphi_{n},n}$ on the Hardy and weighted Bergman spaces. We describe the…

Functional Analysis · Mathematics 2021-08-13 Mahsa Fatehi

In this paper, we study hyponormal weighed composition operators on the Hardy and weighted Bergman spaces. For functions $\psi \in A(\mathbb{D})$ which are not the zero function, we characterize all hyponormal compact weighted composition…

Functional Analysis · Mathematics 2016-02-01 Mahsa Fatehi , Mahmood Haji Shaabani

Suppose $n\geq 3$ and let $B$ be the open unit ball in $\mathbb{R}^n$. Let $\varphi: B\to B$ be a $C^2$ map whose Jacobian does not change sign, and let $\psi$ be a $C^2$ function on $B$. We characterize bounded weighted composition…

Complex Variables · Mathematics 2017-08-18 Pengyan Hu , Congwen Liu , Taishun Liu , Lifang Zhou

In this paper, we prove that the null space of a weighted composition operator on $\ell_p~ (1 \leq p < \infty)$ is a complemented subspace. We also give a necessary and sufficient condition for a weighted composition operator on $\ell_p$…

Functional Analysis · Mathematics 2024-02-15 Anurag Kumar Patel

We completely characterize the spectrum of a weighted composition operator $W_{\psi, \varphi}$ on $H^{2}(\mathbb{D})$ when $\varphi$ has Denjoy-Wolff point $a$ with $0<|\varphi '(a)|< 1$, the iterates, $\varphi_{n}$, converge uniformly to…

Functional Analysis · Mathematics 2017-05-17 Carl Cowen , Eungil Ko , Derek Thompson , Feng Tian

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

A characterization of those points in the unit disc which belong to the spectrum of a composition operator $C_{\varphi}$, defined by a rotation $\varphi(z)=rz$ with $|r|=1$, on the space $H_0(\mathbb{D})$ of all analytic functions on the…

Functional Analysis · Mathematics 2020-01-15 José Bonet

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

By a theorem of Gordon and Hedenmalm, $\varphi$ generates a bounded composition operator on the Hilbert space $\mathscr{H}^2$ of Dirichlet series $\sum_n b_n n^{-s}$ with square-summable coefficients $b_n$ if and only if $\varphi(s)=c_0…

Functional Analysis · Mathematics 2015-02-23 Hervé Queffélec , Kristian Seip

We provide an estimate for the essential norm of a weighted composition operator $W_{\psi,\varphi}\colon f\mapsto \psi(f\circ\varphi)$ acting on the space $BMOA$ in terms of the weight function $\psi$ and the $n$-th power $\varphi^n$ of the…

Functional Analysis · Mathematics 2013-12-06 Jussi Laitila , Mikael Lindström

If $\psi$ is analytic on the open unit disk $\mathbb{D}$ and $\varphi$ is an analytic self-map of $\mathbb{D}$, the weighted composition operator $C_{\psi,\varphi}$ is defined by $C_{\psi,\varphi}f(z)=\psi(z)f (\varphi (z))$, when $f$ is…

Functional Analysis · Mathematics 2016-02-11 Mahsa Fatehi , Mahmood Haji Shaabani

The spectrum of a weighted composition operator $C_{\psi, \varphi}$ who is induced by an automorphism has been investigated for over fifty years. However, many results are got only under the condition that the weight function $\psi$ is…

Functional Analysis · Mathematics 2020-12-01 Xing-Tang Dong , Yong-Xin Gao , Ze-Hua Zhou

We study the numerical range of the Weighted Composition Operator over the Mittag-Leffler space of entire functions.

Functional Analysis · Mathematics 2021-10-22 Himanshu Singh

We study various properties of composition operators acting between generalized Fock spaces $\mathcal{F}_\varphi^p$ and $\mathcal{F}_\varphi^q$ with weight functions $\varphi$ grow faster than the classical Gaussian weight function…

Complex Variables · Mathematics 2020-01-23 Tesfa Mengestie , Werkaferahu Seyoum

By a theorem of Bayart, $\varphi$ generates a bounded composition operator on the Hardy space $\Hp$of Dirichlet series ($1\le p<\infty$) only if $\varphi(s)=c_0 s+\psi(s)$, where $c_0$ is a nonnegative integer and $\psi$ a Dirichlet series…

Functional Analysis · Mathematics 2016-02-26 Frédéric Bayart , Hervé Queffélec , Kristian Seip

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

We study the approximation numbers of weighted composition operators $f\mapsto w\cdot(f\circ\varphi)$ on the Hardy space $H^2$ on the unit disc. For general classes of such operators, upper and lower bounds on their approximation numbers…

Functional Analysis · Mathematics 2017-12-27 Gandalf Lechner , Daniel Li , Hervé Queffélec , Luis Rodríguez-Piazza

Let $\psi$ be a holomorphic function on the open unit ball $\BB \subset \C^N$, and let $\varphi$ be a holomorphic self-map of $\BB$, associated with normal weights $\nu$ and $\mu$. We consider the weighted composition operator $…

Complex Variables · Mathematics 2025-10-17 Thai Thuan Quang
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