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We introduce a Cherednik kernel and a hypergeometric function for integral root systems and prove their relation to spherical functions associated with Riemannian symmetric spaces of reductive Lie groups. Furthermore, we characterize the…

Classical Analysis and ODEs · Mathematics 2024-10-10 Dominik Brennecken

We prove the corona theorem for domains whose boundary lies in certain smooth quasicircles. These curves, which are not necessarily Dini-smooth, are defined by quasiconformal mappings whose complex dilatation verifies certain conditions.…

Complex Variables · Mathematics 2018-11-13 J. M. Enriquez-Salamanca , Maria J. Gonzalez

Let ${\rm {\mathbb G}}$ be a domain with closed rectifiable Jordan curve $\ell $ . Let $K({\rm {\mathbb G}})$ be the space of all analytic functions in ${\rm {\mathbb G}} $ representable by a Cauchy - Stieltjes integral. Let ${\rm…

Complex Variables · Mathematics 2009-01-14 Peyo Stoilov

The Fourier transform and its inverse are well-known to have complex conjugate integral kernels. S.~Saitoh demonstrated that this relationship extends to the theory of integral transforms of Hilbert spaces of functions under certain…

Functional Analysis · Mathematics 2024-12-30 Akira Yamada

We investigate multipliers on the space of holomorphic functions $H(\Omega)$, where $\Omega \subset \mathbb{C}^n$ is an open set. For Runge domains, we characterize these multipliers as convolutions with analytic functionals. Additionally,…

Functional Analysis · Mathematics 2025-09-24 Maria Trybuła

The bicomplex Bergman spaces are studied for any bounded bicomplex domain. Its Bergman kernel is computed in terms of the kernels of the complex projections of the domain. We also introduce two additional reproducing kernel Hilbert spaces…

Functional Analysis · Mathematics 2024-02-21 Cesar O. Perez-Regalado , Raul Quiroga-Barranco

Tolokonnikov's Corona Theorem is used to obtain two results on cyclicity in Besov-Dirichlet spaces.

Classical Analysis and ODEs · Mathematics 2024-05-17 Yabreb Mohamed Egueh , Karim Kellay , Mohamed Zarrabi

In this note, we describe the backward shift invariant subspaces for a large class of reproducing kernel Hilbert spaces. This class includes in particular de Branges-Rovnyak spaces (the non-extreme case) and the range space of co-analytic…

Functional Analysis · Mathematics 2019-04-08 Emmanuel Fricain , Javad Mashreghi , Rishika Rupam

The study of Cowen-Douglas operators not only involves traditional operator-theoretic tools but also concepts and results from complex geometry on holomorphic vector bundles. We make use of the ratio of the metric matrices first considered…

Functional Analysis · Mathematics 2025-06-24 Kui Ji , Shanshan Ji , Hyun-Kyoung Kwon , Jing Xu

We prove multiplier theorems on rank one noncompact symmetric spaces which improve aspects of existing results. A common theme of our main results is that we partially drop specific assumptions on the multiplier function such as a…

Functional Analysis · Mathematics 2023-05-11 Błażej Wróbel

Let T be a C_{\cdot 0}-contraction on a Hilbert space H and S be a non-trivial closed subspace of H. We prove that S is a T-invariant subspace of H if and only if there exists a Hilbert space D and a partially isometric operator \Pi :…

Functional Analysis · Mathematics 2013-10-01 Jaydeb Sarkar

The solvability of the Riemann-Hilbert boundary value problem on the real line is described in the case when its matrix coefficient admits a Wiener-Hopf type factorization with bounded outer factors but rather general diagonal elements of…

Functional Analysis · Mathematics 2011-03-11 M. C. Camara , C. Diogo , Yu. I. Karlovich , I. M. Spitkovsky

We study from the perspective of Borel complexity theory the classification problem for multiplier algebras associated with operator algebraic varieties. These algebras are precisely the multiplier algebras of irreducible complete…

Operator Algebras · Mathematics 2020-09-23 Michael Hartz , Martino Lupini

For a planar domain $\Omega$, we consider the Dirichlet spaces with respect to a base point $\zeta\in\Omega$ and the corresponding kernel functions. It is not known how these kernel functions behave as we vary the base point. In this note,…

Complex Variables · Mathematics 2025-03-10 Sahil Gehlawat , Aakanksha Jain , Amar Deep Sarkar

We study a reproducing kernel Hilbert space of functions defined on the positive integers and associated to the binomial coefficients. We introduce two transforms, which allow us to develop a related harmonic analysis in this Hilbert space.…

Complex Variables · Mathematics 2014-12-19 Daniel Alpay , Palle Jorgensen

We use a classical characterisation to prove that functions which are bounded away from zero cannot be elements of reproducing kernel Hilbert spaces whose reproducing kernels decays to zero in a suitable way. The result is used to study…

Functional Analysis · Mathematics 2021-02-23 Toni Karvonen

We study the structure of the maximal ideal space $M(H^{\infty})$ of the algebra $H^{\infty}=H^{\infty}(\Di)$ of bounded analytic functions defined on the open unit disk $\Di\subset\Co$. Based on the fact that $dim\ M(H^{\infty})=2$ we…

Complex Variables · Mathematics 2007-05-23 Alexander Brudnyi

The object of this paper is to prove a version of the Beurling-Helson-Lowdenslager invariant subspace theorem for operators on certain Banach spaces of functions on a multiply connected domain in the complex plane. The norms for these…

Functional Analysis · Mathematics 2016-07-06 Yanni Chen , Don Hadwin , Zhe Liu , Eric Nordgren

We begin a coarse geometric study of Hilbert geometry. Actually we give a necessary and sufficient condition for the natural boundary of a Hilbert geometry to be a corona, which is a nice boundary in coarse geometry. In addition, we show…

Metric Geometry · Mathematics 2017-05-02 Ryosuke Mineyama , Shin-ichi Oguni

We show that kernel-based quadrature rules for computing integrals can be seen as a special case of random feature expansions for positive definite kernels, for a particular decomposition that always exists for such kernels. We provide a…

Machine Learning · Computer Science 2015-11-10 Francis Bach