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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 consider operators acting on a Hilbert space that can be written as the sum of a shift and a diagonal operator and determine when the operator is hyponormal. The condition is presented in terms of the norm of an explicit block Jacobi…

Classical Analysis and ODEs · Mathematics 2021-08-11 Trieu Le , Brian Simanek

In this paper, we obtain a complete characterization for the compact difference of two composition operators acting on Bergman spaces with a rapidly decreasing weight $\omega=e^{-\eta}$, $\Delta\eta>0$. In addition, we provide simple…

Functional Analysis · Mathematics 2024-07-23 Inyoung Park

A complete characterisation is given of all the linear isometries of the Fr\'echet space of all holomorphic functions on the unit disc, when it is given one of the two standard metrics: these turn out to be weighted composition operators of…

Complex Variables · Mathematics 2024-05-17 I. Chalendar , L. Oger , J. R. Partington

A linear operator $U$ acting boundedly on an infinite-dimensional separable complex Hilbert space $H$ is universal if every linear bounded operator acting on $H$ is similar to a scalar multiple of a restriction of $U$ to one of its…

Functional Analysis · Mathematics 2024-06-05 Luciano Abadías , F. Javier González-Doña , Jesús Oliva-Maza

We investigate composition-differentiation operators acting on the Dirichlet space of the unit disk. Specifically, we determine characterizations for bounded, compact, and Hilbert-Schmidt composition-differentiation operators. In addition,…

Functional Analysis · Mathematics 2022-07-26 Robert F. Allen , Katherine Heller , Matthew A. Pons

We compute the spectra and the essential spectra of bounded linear fractional composition operators acting on the Hardy and weighted Bergman spaces of the upper half-plane. We are also able to extend the results to weighted Dirichlet spaces…

Functional Analysis · Mathematics 2016-11-28 Riikka Schroderus

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 the operad of holomorphic disk embeddings of the unit disk $\mathbb D \subset \mathbb C$. We introduce a suboperad $\mathbb{CE}_2^{HS}$ defined by square-integrability conditions and show that the symmetric algebra…

Quantum Algebra · Mathematics 2026-03-09 Yuto Moriwaki

In this paper we characterize the compact operators on the Bergman space $A^p(\mathbb{D}^n)$. The main result shows that an operator on $A^p(\mathbb{D}^n)$ is compact if and only if it belongs to the Toeplitz algebra $\mathcal{T}_{p}$ and…

Complex Variables · Mathematics 2013-08-20 Mishko Mitkovski , Brett D. Wick

In this paper we investigate weighted composition operators between weak and strong vector valued weighted Bergman spaces and Hardy spaces.

Functional Analysis · Mathematics 2012-11-28 Mostafa Hassanlou , Hamid Vaezi

Let $\Omega\subset \mathbb{C}^n$ be a smooth bounded pseudoconvex domain and $A^2 (\Omega)$ denote its Bergman space. Let $P:L^2(\Omega)\longrightarrow A^2(\Omega)$ be the Bergman projection. For a measurable $\varphi:\Omega\longrightarrow…

Complex Variables · Mathematics 2021-05-25 Zeljko Cuckovic

In this paper we give sharp norm estimates for the Bergman operator acting from weighted mixed-norm spaces to weighted Hardy spaces in the ball, endowed with natural norms.

Complex Variables · Mathematics 2015-01-12 C. Cascante , J. Fabrega , J. M. Ortega

We characterize the (essentially) decreasing sequences of positive numbers $\beta$ = ($\beta$ n) for which all composition operators on H 2 ($\beta$) are bounded, where H 2 ($\beta$) is the space of analytic functions f in the unit disk…

Functional Analysis · Mathematics 2022-03-22 Pascal Lefèvre , Daniel Li , Hervé Queffélec , Luis Rodríguez-Piazza

Let $D$ be a bounded homogeneous domain in $\mathbb{C}^n$. In this paper, we study the bounded and the compact weighted composition operators mapping the Hardy space $H^\infty(D)$ into the Bloch space of $D$. We characterize the bounded…

Functional Analysis · Mathematics 2022-07-26 Robert F. Allen , Flavia Colonna

We obtain necessary and sufficient conditions for the composition and weighted composition operator and product of composition operators to be isometry and unitary on $H_{E}(\xi).$ With the help of counter example we also prove that the…

Functional Analysis · Mathematics 2021-10-25 Anuradha Gupta , Geeta Yadav

In this paper we show that a composition operator $C_\varphi$ cannot be complex symmetric on Hardy-Hilbert space $H^2(D)$ when $\varphi$ is an elliptic automorphism of order $3$ and not a rotation. This completes the project of finding all…

Functional Analysis · Mathematics 2016-08-02 Yong-Xin Gao , Ze-Hua Zhou

In this paper we propose a different (and equivalent) norm on $S^{2} ({\mathbb{D}})$ which consists of functions whose derivatives are in the Hardy space of unit disk. The reproducing kernel of $S^{2}({\mathbb{D}})$ in this norm admits an…

Functional Analysis · Mathematics 2018-08-31 Caixing Gu , Shuaibing Luo

We consider this and related questions: When is a finite linear combination of composition operators, acting on the Hardy space or the standard weighted Bergman spaces on the unit disk, a compact operator?

Functional Analysis · Mathematics 2007-05-23 Thomas Kriete , Jennifer Moorhouse

This paper studies the \(k^{th}-\)order slant Toeplitz and slant little Hankel operators on the weighted Bergman space \(\mathcal{A}_\alpha^2(\mathbb{D})\). These operators are constructed using a slant shift operator \(W_k\) composed with…

Functional Analysis · Mathematics 2025-07-10 Oinam Nilbir Singh , M. P. Singh , Thokchom Sonamani Singh