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It is shown that every algebra over the chain operad of the little disks operad gives naturally rise to a Hertling-Manin's F-manifold, that is a smooth manifold equipped with an integrable graded commutative associative product on the…

Algebraic Geometry · Mathematics 2007-05-23 S. A. Merkulov

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

This paper provides a class of complex symmetric weighted composition operators on $H^2(\mathbb{D})$ to includes the unitary subclass, the Hermitian subclass and the normal subclass obtained by Bourdon and Noor. A characterization of…

Functional Analysis · Mathematics 2018-12-27 Cao Jiang , Shi-An Han , 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

In this paper we study the complex symmetry in the several variable Fock space by using the techniques of weighted composition operators and semigroups. We characterize unbounded weighted composition operators that are (real) complex…

Functional Analysis · Mathematics 2023-12-11 Pham Viet Hai , Pham Trong Tien

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

This paper aims to study the boundedness and compactness of composition operators from model spaces to the Hardy Hilbert spaces in the upper half-plane. Consequently, we investigate the boundedness and compactness of composition operators…

Functional Analysis · Mathematics 2026-05-13 Bharti Garg , Subhankar Mahapatra , Santanu Sarkar

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

When $\varphi$ and $\psi$ are linear-fractional self-maps of the unit ball $B_N$ in ${\mathbb C}^N$, $N\geq 1$, we show that the difference $C_{\varphi}-C_{\psi}$ cannot be non-trivially compact on either the Hardy space $H^2(B_N)$ or any…

Functional Analysis · Mathematics 2010-06-11 Katherine Heller , Barbara D. MacCluer , Rachel J. Weir

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 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

In 1987, Shapiro shew that composition operator induced by symbol $\phi$ is compact on the Lipschltz space if and only if the infinity norm of $\phi$ is less than 1 by a spectral-theoretic argument, where $\phi$ is a holomorphic self-map of…

Functional Analysis · Mathematics 2013-12-30 Zhongshan Fang , Zehua Zhou

We study the compactly supported rational cohomology of configuration spaces of points on wedges of spheres, equipped with natural actions of the symmetric group and the group $Out(F_g)$ of outer automorphisms of the free group. These…

Algebraic Topology · Mathematics 2025-06-13 Nir Gadish , Louis Hainaut

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

Let $\phi$ be an analytic self-map and $u$ be a fixed analytic function on the open unit disk $D$ in the complex plane $\CC.$ The weighted composition operator is defined\break by \begin{equation*} uC_\phi f =u \cdot (f\circ \phi), f \in…

Complex Variables · Mathematics 2007-09-24 Songxiao Li , Stevo Stević

By a theorem of Gordon and Hedenmalm, $\varphi$ generates a bounded composition operator on the Hilbert space $\mathscr{H}^2$ of Dirichlet series $\sum_n b_n n^{-s}$ with square-summable coefficients $b_n$ if and only if $\varphi(s)=c_0…

Functional Analysis · Mathematics 2015-02-23 Hervé Queffélec , Kristian Seip

We consider symmetry operators a from the group ring C[S_N] which act on the Hilbert space H of the 1D spin-1/2 Heisenberg magnetic ring with N sites. We investigate such symmetry operators a which are self-adjoint (in a sence defined in…

Combinatorics · Mathematics 2015-05-14 Bernd Fiedler

Let $\Omega$ be a bounded symmetric domain except the two exceptional domains of ${\Bbb C}^N$ and $\phi$ a holomorphic self-map of $\Omega.$ This paper gives a sufficient and necessary condition for the composition operator $C_{\phi}$…

Complex Variables · Mathematics 2007-05-23 Zehua Zhou , Yan Liu

Motivated by the study of frame properties arising from iterates of linear operators, it was previously established that the multiplication operator $T_{\phi}x(t) = \phi(t)x(t)$ cannot generate a frame in $L^2(a,b)$ (Results Math, 2019). In…

Functional Analysis · Mathematics 2025-09-08 Jahangir Cheshmavar

We study composition operators on the Hardy space $\mathcal{H}^2$ of Dirichlet series with square summable coefficients. Our main result is a necessary condition, in terms of a Nevanlinna-type counting function, for a certain class of…

Functional Analysis · Mathematics 2022-12-27 Athanasios Kouroupis
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