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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

In this paper, we investigate the spectra of invertible weighted composition operators with automorphism symbols, on Hardy space $H^2(\mathbb{B}_N)$ and weighted Bergman spaces $A_\alpha^2(\mathbb{B}_N)$, where $\mathbb{B}_N$ is the unit…

Functional Analysis · Mathematics 2014-06-19 Yong-Xin Gao , Ze-Hua Zhou

We investigate the bounded composition operators induced by linear fractional self-maps of the right half-plane $\mathbb{C}_+$ on the Hardy space $H^2(\mathbb{C}_+).$ We completely characterize which of these operators are cohyponormal and…

Functional Analysis · Mathematics 2025-06-30 V. V. Fávaro , P. V. Hai , O. R. Severiano

Previously, spectra of certain weighted composition operators on the Hardy Space were discovered under one of two hypotheses: either the compositional symbol converges under iteration to the Denjoy-Wolff point on all of the open disk rather…

Functional Analysis · Mathematics 2021-11-16 Jessica Doctor , Timothy Hodges , Scott Kaschner , Alexander McFarland , Derek Thompson

We characterize the spectrum and essential spectrum of "essentially linear fractional" composition operators acting on the Hardy space H-two of the open unit disc U. When the symbols of these composition operators have Denjoy-Wolff point on…

Functional Analysis · Mathematics 2009-08-12 Paul S. Bourdon

In this paper, we find complex symmetric composition operators on the classical Hardy space whose symbols are linear-fractional but not automorphic. In doing so, we answer a recent question of Noor, and partially answer the original problem…

Complex Variables · Mathematics 2017-05-17 Sivaram K. Narayan , Daniel Sievewright , Derek Thompson

Let $\varphi$ be a linear fractional self-map of the open unit disk $\mathbb{D}$ and $H^2$ the Hardy space of analytic functions on $\mathbb{D}$. The goal of this article is to characterize the linear fractional composition operators…

Functional Analysis · Mathematics 2018-09-26 S. Waleed Noor

In this paper we investigate the numerical ranges of composition operators whose symbols are elliptic automorphisms of finite orders, on the Hilbert Hardy space $H^2(D)$.

Functional Analysis · Mathematics 2023-02-22 Yong-Xin Gao , Ze-Hua Zhou

In the paper we give the results about the spectra of non-invertible weighted composition operators induced by automorphisms on several Hilbert spaces, such as Hardy-Hilbert space $H^2(\mathbb{D})$ and weighted Bergman spaces…

Functional Analysis · Mathematics 2017-07-14 Yong-Xin Gao , Ze-Hua Zhou

We prove that a composition operator is bounded on the Hardy space $H^2$ of the right half-plane if and only if the inducing map fixes the point at infinity non-tangentially, and has a finite angular derivative $\lambda$ there. In this case…

Functional Analysis · Mathematics 2014-02-26 Sam Elliott , Michael T. Jury

Let H^2(D) denote the classical Hardy space of the open unit disk D in the complex plane. We obtain descriptions of both the spectrum and essential spectrum of composition operators on H^2(D) whose symbols belong to the class S(2)…

Functional Analysis · Mathematics 2015-01-05 Paul S. Bourdon

We realize norms of most composition operators acting on the Hardy space with linear fractional symbol as roots of hypergeometric functions. This realization leads to simple necessary and sufficient conditions on the symbol to exhibit…

Complex Variables · Mathematics 2007-05-23 Estelle L. Basor , Dylan Q. Retsek

We consider the products of composition and differentiation operators on the Hardy space. We provide a complete characterization of the boundedness and compactness of these operators. Furthermore, we obtain the explicit condition for these…

Functional Analysis · Mathematics 2021-08-17 Mahbube Moradi , Mahsa Fatehi

It is well known that on the Hardy space $H^2(\mathbb{D})$ or weighted Bergman space $A^2_{\alpha}(\mathbb{D})$ over the unit disk, the adjoint of a linear fractional composition operator equals the product of a composition operator and two…

Functional Analysis · Mathematics 2015-09-07 Zeljko Cuckovic , Trieu Le

In this paper, we study 2-complex symmetric composition operators with the conjugation $J$ on the Hardy space $H^2$. More precisely, we obtain the necessary and sufficient condition for the composition operator $C_\phi$ to be 2-complex…

Complex Variables · Mathematics 2021-10-22 Lian Hu , Songxiao Li , Rong Yang

In this work we study the essential spectra of composition operators on Hardy spaces of analytic functions which might be termed as "quasi-parabolic". This is the class of composition operators on H^{2} with symbols whose conjugate with the…

Functional Analysis · Mathematics 2013-10-31 Ugur Gul

Let $\phi$ be a holomorphic self-map of the open unit disk $\mathbb{D}.$ In this article, we study the shadowing phenomenon for composition operators $C_{\phi}f=f\circ \phi$ on the Hardy space $H^2(\mathbb{D}).$ We mainly characterize all…

Dynamical Systems · Mathematics 2026-03-12 Artur Blois , Ben-Hur Eidt , Paulo Lupatini , Osmar R. Severiano

In this paper, we study quasinormal and hyponormal composition operators \W with linear fractional compositional symbol $\ph$ on the Hardy and weighted Bergman spaces. We characterize the quasinormal composition operators induced on $H^{2}$…

Functional Analysis · Mathematics 2017-05-17 Mahsa Fatehi , Mahmood Haji Shaabani , Derek Thompson

We give a complete characterization of the sequences $\beta = (\beta_n)$ of positive numbers for which all composition operators on $H^2 (\beta)$ are bounded, where $H^2 (\beta)$ is the space of analytic functions $f$ on the unit disk…

Complex Variables · Mathematics 2023-12-07 Pascal Lefèvre , Daniel Li , Hervé Queffélec , Luis Rodríguez-Piazza

In this paper, we investigate when weighted composition operators acting on Dirichlet spaces $\mathcal{D}(\mathbb{B}_{N})$ are complex symmetric with respect to some special conjugations, and provide some characterizations of Hermitian…

Functional Analysis · Mathematics 2018-12-27 Xiao-He Hu , Zi-Cong Yang , Ze-Hua Zhou
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