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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

We generalize, on one hand, some results known for composition operators on Hardy spaces to the case of Hardy-Orlicz spaces $H^\Psi$: construction of a "slow" Blaschke product giving a non-compact composition operator on $H^\Psi$;…

Functional Analysis · Mathematics 2010-01-20 Pascal Lefèvre , Daniel Li , Hervé Queffélec , Luis Rodriguez-Piazza

We propose a survey on composition operators in classical Sobolev spaces. We mention results obtained in 2019, on the continuity of such operators.

Functional Analysis · Mathematics 2022-07-12 Gérard Bourdaud

We investigate the compactness of composition operators on the Hardy space of Dirichlet series induced by a map $\varphi(s)=c_0s+\varphi_0(s)$, where $\varphi_0$ is a Dirichlet polynomial. Our results depend heavily on the characteristic…

Functional Analysis · Mathematics 2018-03-16 Frédéric Bayart , Ole Fredrik Brevig

In this paper, first we characterize closedness of range of the finite sum of weighted composition operators between different Lp-spaces. Then we discuss polar decomposition and invertibility of these operators.

Functional Analysis · Mathematics 2019-07-23 Saeedeh Shamsigamchi , Abolghasem Alishahi , Ali Ebadian

We study composition operators on spaces of holomorphic Lipschitz functions defined on the open unit ball of a complex Banach space. Our approach is based on the linearization of the symbol through the holomorphic Lipschitz-free spaces,…

Functional Analysis · Mathematics 2026-05-21 Verónica Dimant , Luis C. García-Lirola , Juan Guerrero-Viu , Antonín Procházka

We investigate composition-differentiation operators acting on the space $S^2$, the space of analytic functions on the open unit disk whose first derivative is in $H^2$. Specifically, we determine characterizations for bounded and compact…

Functional Analysis · Mathematics 2022-08-09 Robert F. Allen , Katherine Heller , Matthew A. Pons

We give embedding theorems for weighted Bergman-Orlicz spaces on the ball and then apply our results to the study of composition operators in this context. As one of the motivations of this work, we show that there exist some weighted…

Functional Analysis · Mathematics 2010-12-06 Stéphane Charpentier

In this article we obtain estimates of Neumann eigenvalues of $p$-Laplace operators in a large class of space domains satisfying quasihyperbolic boundary conditions. The suggested method is based on composition operators generated by…

Analysis of PDEs · Mathematics 2020-08-26 Vladimir Gol'dshtein , Ritva Hurri-Syrjänen , Valerii Pchelintsev , Alexander Ukhlov

The main purpose of the paper is to study sharp estimates of approximation of periodic functions in the H\"older spaces $H_p^{r,\alpha}$ for all $0<p\le\infty$ and $0<\alpha\le r$. By using modifications of the classical moduli of…

Classical Analysis and ODEs · Mathematics 2015-07-28 Yurii Kolomoitsev , Jürgen Prestin

Let $\varphi: B_d\to\mathbb{D}$, $d\ge 1$, be a holomorphic function, where $B_d$ denotes the open unit ball of $\mathbb{C}^d$ and $\mathbb{D}= B_1$. Let $\Theta: \mathbb{D} \to \mathbb{D}$ be an inner function and let $K^p_\Theta$ denote…

Complex Variables · Mathematics 2026-01-14 Evgueni Doubtsov

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 obtain $H^{p}_{w} - L^{q}_{w^{q/p}}$ estimates for certain fractional operators.

Classical Analysis and ODEs · Mathematics 2022-01-25 Pablo Rocha

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

This article presents a formula for some dispersionless equations and a brief review of the operators which have been used for the dispersionless KP hierarchy.

High Energy Physics - Theory · Physics 2008-02-03 Seung Hwan Son

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

In this paper we initiate the study of composition operators on the noncommutative Hardy space $H^2_{\bf ball}$. Several classical results about composition operators (boundedness, norm estimates, spectral properties, compactness,…

Functional Analysis · Mathematics 2011-11-15 Gelu Popescu

We show that the already known results for a composition operator to have closed range on H2 (Cima, Thomson, and Wogen (1974), Zorboska (1994)) can be extended to Hp for p>0 .

Complex Variables · Mathematics 2020-03-02 Petros Galanopoulos , Kostas Panteris

Let $\mathscr{H}^2$ denote the Hilbert space of Dirichlet series with square-summable coefficients. We study composition operators $\mathscr{C}_\varphi$ on $\mathscr{H}^2$ which are generated by symbols of the form $\varphi(s) = c_0s +…

Functional Analysis · Mathematics 2021-12-17 Ole Fredrik Brevig , Karl-Mikael Perfekt

We obtain criteria for the boundedness and compactness of weighted composition operators between different Fock spaces in $\mathbb{C}^n$. We also give estimates for essential norm of these operators.

Complex Variables · Mathematics 2018-01-26 Pham Trong Tien , Le Hai Khoi