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Bounded and compact differences of two composition operators acting from the weighted Bergman space $A^p_\omega$ to the Lebesgue space $L^q_\nu$, where $0<q<p<\infty$ and $\omega$ belongs to the class $\mathcal{D}$ of radial weights…

Complex Variables · Mathematics 2020-07-10 Bin Liu , Jouni Rättyä , Fanglei Wu

We obtain sufficient conditions for a densely defined operator on the Fock space to be bounded or compact. Under the boundedness condition we then characterize the compactness of the operator in terms of its Berezin transform.

Functional Analysis · Mathematics 2012-11-30 Xiaofeng Wang , Guangfu Cao , Kehe Zhu

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 first obtain a simpler proof of the main results in [IEOT, {\bf 93}(2021), 17], which characterized the bounded and compact differences $C_{u,\varphi}-C_{v,\psi}$ of two weighted composition operators acting from…

Functional Analysis · Mathematics 2025-07-29 Jiaoye Du , Cezhong Tong , Zicong Yang

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

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

Bounded weighted composition operators, as well as compact weighted composition operators, on Fock spaces have been characterised. This characterisation is refined to the extent that the question of whether weighted composition operators on…

Functional Analysis · Mathematics 2021-04-26 Tom Carroll , Clifford Gilmore

Let $\lambda_i (i=1,...,k)$ be any nonzero complex scalars and $\varphi_i (i=1,..,k)$ be any analytic self-maps of the unit disk $\mathbb{D}$. We show that the operator $\sum_{i=1}^k\lambda_iC_{\varphi_i}$ is compact on the Bloch space…

Complex Variables · Mathematics 2018-02-13 Yecheng Shi , Songxiao Li

We establish a new $T1$ theorem for the compactness of bi-parameter Calder\'on-Zygmund singular integral operators. Namely, we show that if a bi-parameter CZO $T$ satisfies the product weak compactness property, the mixed weak…

Classical Analysis and ODEs · Mathematics 2026-01-12 Cody B. Stockdale , Cody Waters

We introduce an ordinal index which characterizes weak compactness of operators between Banach spaces. We study when classes consisting of operators having bounded index form a closed ideal, the distinctness of the classes, and the…

Functional Analysis · Mathematics 2015-08-25 Ryan M. Causey

We consider composition operators in the Dirichlet space of the unit disc in the plane. Various criteria on boundedness, compactness and Hilbert-Schmidt class membership are established. Some of these criteria are shown to be optimal.

Functional Analysis · Mathematics 2010-12-30 O. El-Fallah , K. Kellay , M. Shabankhah , H. Youssfi

In this study, we investigate the boundedness of composition operators acting on Morrey spaces and weak Morrey spaces. The primary aim of this study is to investigate a necessary and sufficient condition on the boundedness of the…

Functional Analysis · Mathematics 2020-08-31 Naoya Hatano , Masahiro Ikeda , Isao Ishikawa , Yoshihiro Sawano

Weakly centered and spectrally weakly cenetered weighted composition operators in $L^2$-spaces are characterized. Criteria for existence of invariant subspaces are given. Additional results and examples are supplied.

Functional Analysis · Mathematics 2025-10-23 Piotr Budzyński

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

When G is a region in the complex plane, compact composition operators on the uniform algebra of bounded analytic functions on G and the spectra of these operators were described by D. Swanton, Compact composition operators on B(D), Proc.…

Functional Analysis · Mathematics 2007-05-23 J. F. Feinstein , Herbert Kamowitz

We study boundedness and compactness of composition operators on weighted Bergman spaces of Dirichlet series. Particularly, we obtain in some specific cases, upper and lower bounds of the essential norm of these operators and a criterion of…

Functional Analysis · Mathematics 2014-01-30 Maxime Bailleul

In this paper, we investigate necessary and sufficient conditions on the boundedness of composition operators on the Orlicz-Morrey spaces. The results of boundedness include Lebesgue and generalized Morrey spaces as special cases. Further,…

Functional Analysis · Mathematics 2024-04-16 Masahiro Ikeda , Isao Ishikawa , Ryota Kawasumi

We give a necessary and sufficient condition for a holomorphic self-map $\phi$ of the tridisc to induce a bounded composition operator on the associated Hardy space. This condition depends on the behaviour of the first and the second…

Functional Analysis · Mathematics 2023-12-06 Frédéric Bayart

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

In this paper we characterize some basic properties of composition operators on the spaces of harmonic Bloch functions. First we provide some equivalent conditions for boundedness and compactness of composition operators. Then by using…

Functional Analysis · Mathematics 2018-12-27 Y. Estaremi , S. Esmaili , A. Ebadian