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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 $\phi$ 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

Let $\zeta$ and $\eta$ be distinct points on the unit circle and suppose that $\phi$ is a linear-fractional self-map of the unit disk D, not an automorphism, with $\phi(\zeta)=\eta$. We describe the C*-algebra generated by the associated…

Operator Algebras · Mathematics 2007-05-23 Thomas L. Kriete , Barbara D. MacCluer , Jennifer L. Moorhouse

In this paper we show that every conjugation $C$ on the Hardy-Hilbert space $H^{2}$ is of type $C=T^{*}C_{1}T$, where $T$ is an unitary operator and $C_{1}f\left(z\right)=\overline{f\left(\overline{z}\right)}$, with $f\in H^{2}$. In the…

Functional Analysis · Mathematics 2022-02-01 Marcos S. Ferreira

In this paper, we investigate the normal weighed composition operators $W_{\psi,\varphi}$ which is $\mathcal{J}-$symmetric, $\mathcal{C}_1-$symmetric and $\mathcal{C}_2-$symmetric on the Hardy space $H^2(\mathbb{D})$ respectively. Firstly,…

Functional Analysis · Mathematics 2019-01-04 Hang Zhou , Ze-Hua Zhou

In this paper we provide a full characterization of cyclic composition operators defined on the d-dimensional Fock space $\mathcal F(\mathbb C^d)$ in terms of their symbol. Also, we study the supercyclicity and convex-cyclicity of this type…

Functional Analysis · Mathematics 2022-05-24 Frédéric Bayart , Sebastián Tapia-García

In this article, we introduce a new class of conjugations in the scalar valued Hardy space $H^2_{\mathbb{C}}(\mathbb{D})$ and provide a characterization of a complex symmetric Toeplitz operator $T_{\phi}$ with respect to these newly…

Functional Analysis · Mathematics 2021-08-17 Arup Chattopadhyay , Soma Das , Chandan Pradhan , Srijan Sarkar

In this paper, we introduce a general class of weighted spaces of holomorphic Dirichlet series (with real frequencies) analytic in some half-plane and study composition operators on these spaces. In the particular case when the symbol…

Functional Analysis · Mathematics 2021-04-15 Emmanuel Fricain , Camille Mau

We study the C$^*$ algebra generated by the composition operator $C_a$ acting on the Hardy space $H^2$ of the unit disk, given by $C_af=f\circ\varphi_a$, where $$ \varphi_a(z)=\frac{a-z}{1-\bar{a}z}, $$ for $|a|<1$. Also several operators…

Operator Algebras · Mathematics 2025-04-22 Esteban Andruchow

For 0 < s < 1, let phi_s(z)=sz+(1-s). We investigate the unital C*-algebra generated by the semigroup {C_{phi_s} : 0 < s < 1} of composition operators acting on the Hardy space of the unit disk. We determine the joint approximate point…

Functional Analysis · Mathematics 2009-09-08 Katie S. Quertermous

We show that every non-compact weighted composition operator $f \mapsto u\cdot (f\circ\phi)$ acting on a Hardy space $H^p$ for $1 \leq p < \infty$ fixes an isomorphic copy of the sequence space $\ell^p$ and therefore fails to be strictly…

Functional Analysis · Mathematics 2018-09-17 Mikael Lindström , Santeri Miihkinen , Pekka J. Nieminen

Let $\varphi$ be a linear-fractional, non-automorphism self-map of $\mathbb{D}$ that fixes $\zeta \in \mathbb{T}$ and satisfies $\varphi^{\prime}(\zeta) \neq 1$ and consider the composition operator $C_{\varphi}$ acting on the Hardy space…

Functional Analysis · Mathematics 2012-05-28 Katie S. Quertermous

The algebra of Dirichlet series $\mathcal{A}(\mathcal{C}_{+})$ consists on those Dirichlet series convergent in the right half-plane $\mathcal{C}_{+}$ and which are also uniformly continuous there. This algebra was recently introduced by…

Functional Analysis · Mathematics 2023-12-01 Manuel D. Contreras , Carlos Gómez-Cabello , Luis Rodríguez-Piazza

We first consider some questions raised by N. Zorboska in her thesis. In particular she asked for which sequences $\beta$ every symbol $\varphi \colon \mathbb{D} \to \mathbb{D}$ with $\varphi \in H^2 (\beta)$ induces a bounded composition…

Functional Analysis · Mathematics 2024-05-22 Pascal Lefèvre , Daniel Li , Hervé Queffélec , Luis Rodríguez-Piazza

We characterise hypercyclic composition operators $C_\varphi:f\mapsto f\circ\varphi$ on the space of functions holomorphic on $\Omega$, where $\Omega$ is a connected Stein manifold and $\varphi$ is a holomorphic self-mapping of $\Omega$. In…

Complex Variables · Mathematics 2013-03-15 Sylwester Zajcac

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

In this paper, we consider natural Hilbert-space representations $\left\{ \left(\mathbb{C}^{2},\pi_{t}\right)\right\} _{t\in\mathbb{R}}$ of the hypercomplex system $\left\{ \mathbb{H}_{t}\right\} _{t\in\mathbb{R}}$, and study the…

Representation Theory · Mathematics 2023-01-23 Daniel Alpay , Ilwoo Cho

We use induction and interpolation techniques to prove that a composition operator induced by a map $\phi$ is bounded on the weighted Bergman space $\A^2_\alpha(\mathbb{H})$ of the right half-plane if and only if $\phi$ fixes $\infty$…

Functional Analysis · Mathematics 2009-10-05 Sam Elliott , Andrew Wynn

We give examples of composition operators $C\_\Phi$ on $H^2 (\D^2)$ showing that the condition $\|\Phi \|\_\infty = 1$ is not sufficient for their approximation numbers $a\_n (C\_\Phi)$ to satisfy $\lim\_{n \to \infty} [a\_n (C\_\Phi)…

Functional Analysis · Mathematics 2018-03-05 Daniel Li , Hervé Queffélec , Luis Rodríguez-Piazza

We describe the C*-algebra generated by an irreducible Toeplitz operator $T_{\psi}$, with continuous symbol $\psi $ on the unit circle $\mathbb{T}$, and finitely many composition operators on the Hardy space $H^2$ induced by certain…

Operator Algebras · Mathematics 2014-08-06 Masoud Salehi Sarvestani , Massoud Amini