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We show that the decay of approximation numbers of compact composition operators on the Dirichlet space $\mathcal{D}$ can be as slow as we wish, which was left open in the cited work. We also prove the optimality of a result of…

Functional Analysis · Mathematics 2014-07-11 Daniel Li , Hervé Queffélec , Luis Rodriguez-Piazza

An estimate for the norm of selfadjoint Toeplitz operators with a radial, bounded and integrable symbol is obtained. This emphasizes the fact that the norm of such operator is strictly less than the supremum norm of the symbol. Consequences…

Functional Analysis · Mathematics 2021-02-04 Antonio Galbis

We explore the norm attainment set and the minimum norm attainment set of a bounded linear operator between Hilbert spaces and Banach spaces. Indeed, we obtain a complete characterization of both the sets, separately for operators between…

Functional Analysis · Mathematics 2024-08-13 Debmalya Sain , Kallol Paul , Kalidas Mandal

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

Any bounded analytic function $g$ induces a bounded integral operator $S_g$ on the Bloch space, the Dirichlet space and $BMOA$ respectively. $S_g$ attains its norm on the Bloch space and $BMOA$ for any $g$, but does not attain its norm on…

Complex Variables · Mathematics 2012-03-23 Chengji Xiong , Junming Liu

We analyse the behaviour of the iterates of composition operators defined by polynomials acting on global classes of ultradifferentiable functions of Beurling type which are invariant under the Fourier transform. In particular, we determine…

Functional Analysis · Mathematics 2025-05-27 Angela A. Albanese , Héctor Ariza

This paper investigates composition operators and weighted composition operators on semi-Hilbert spaces induced by positive multiplication operators on \( L^2(\mu) \). Within the framework of \( A \)-adjoint operators, we characterize…

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

We study power boundedness and related properties such as mean ergodicity for (weighted) composition operators on function spaces defined by local properties. As a main application of our general approach we characterize when (weighted)…

Functional Analysis · Mathematics 2019-03-27 Thomas Kalmes

We study the compactness of composition operators on the Bergman spaces of certain bounded convex domains in $\mathbb{C}^n$ with non-trivial analytic discs contained in the boundary. As a consequence we characterize that compactness of the…

Complex Variables · Mathematics 2022-04-18 Timothy G. Clos

We study some dynamical properties of composition operators defined on the space $\mathcal{P}(^m X)$ of $m$-homogeneous polynomials on a Banach space $X$ when $\mathcal{P}(^m X)$ is endowed with two different topologies: the one of uniform…

Functional Analysis · Mathematics 2020-12-16 David Jornet , Daniel Santacreu , Pablo Sevilla-Peris

The paper considers bounded linear radial operators on the polyanalytic Fock spaces $\mathcal{F}_n$ and on the true-polyanalytic Fock spaces $\mathcal{F}_{(n)}$. The orthonormal basis of normalized complex Hermite polynomials plays a…

Operator Algebras · Mathematics 2020-09-25 Egor A. Maximenko , Ana María Tellería-Romero

A Fock space is introduced that admits an action of a quantum group of type A supplemented with some extra operators. The canonical and dual canonical basis of the Fock space are computed and then used to derive the finite-dimenisonal…

Quantum Algebra · Mathematics 2011-11-09 Shun-Jen Cheng , Weiqiang Wang , R. B. Zhang

We introduce a weakened notion of norm attainment for bounded linear operators between Banach spaces which we call \emph{quasi norm attaining operators}. An operator $T\colon X \longrightarrow Y$ between the Banach spaces $X$ and $Y$ is…

Functional Analysis · Mathematics 2020-04-24 Geunsu Choi , Yun Sung Choi , Mingu Jung , Miguel Martin

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

In this paper, we are interested in studying the set $\mathcal{A}_{\|\cdot\|}(X, Y)$ of all norm-attaining operators $T$ from $X$ into $Y$ satisfying the following: given $\epsilon>0$, there exists $\eta$ such that if $\|Tx\| > 1 - \eta$,…

Functional Analysis · Mathematics 2020-09-01 Sheldon Dantas , Mingu Jung , Óscar Roldán

We introduce and discuss some basic properties of some integral transforms in the framework of specific functional Hilbert spaces, the holomorphic Bargmann-Fock spaces on $\mathbb{C}$ and $\mathbb{C}^2$ and the slice hyperholomorphic…

Complex Variables · Mathematics 2018-03-28 Abdelhadi Benahmadi , Kamal Diki , Allal Ghanmi

We study two classes of bounded operators on mixed norm Lebesgue spaces, namely composition operators and product operators. A complete description of bounded composition operators on mixed norm Lebesgue spaces are given. For a certain…

Functional Analysis · Mathematics 2020-03-25 Nikita Evseev , Alexander Menovschikov

Necessary and sufficient conditions are already known in the Hardy spaces of both the disc and the half plane for a composition operator to be an isometry, by Nordgren in the disc and by Chalendar and Partington in the half plane. All the…

Functional Analysis · Mathematics 2010-06-11 Sam Elliott

We study a composition operator on Lorentz spaces. In particular we provide necessary and sufficient conditions under which a measurable mapping induces a bounded composition operator.

Functional Analysis · Mathematics 2021-05-27 Nikita Evseev

In this paper, we obtain the essential norm estimate for the difference of two weighted composition operators acting on standard weighted Bergman spaces over the unit ball. And we get some characterizations for the difference of weighted…

Functional Analysis · Mathematics 2025-07-29 Xiaohe Hu , Zicong Yang
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