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In this paper, we will characterize those sets, over which every irreducible complete Nevanlinna--Pick space enjoys that its multiplier and supremum norms coincide. Moreover, we will prove that, if there exists an irreducible complete…

Functional Analysis · Mathematics 2024-09-24 Kenta Kojin

We characterize interpolating sequences for multiplier algebras of spaces with the complete Pick property. Specifically, we show that a sequence is interpolating if and only if it is separated and generates a Carleson measure. This…

Functional Analysis · Mathematics 2020-09-23 Alexandru Aleman , Michael Hartz , John E. McCarthy , Stefan Richter

Tensor product of Fock spaces is analogous to the Hardy space over the unit polydisc. This plays an important role in the development of noncommutative operator theory and function theory in the sense of noncommutative polydomains and…

Functional Analysis · Mathematics 2020-04-27 Susmita Das , Deepak Kumar Pradhan , Jaydeb Sarkar

An interesting and recently much studied generalization of the classical Schur class is the class of contractive operator-valued multipliers $S$ for the reproducing kernel Hilbert space ${\mathcal H}(k_{d})$ on the unit ball ${\mathbb…

Classical Analysis and ODEs · Mathematics 2007-05-23 Joseph A. Ball , Vladimir Bolotnikov , Quanlei Fang

Using $q$-calculus we study a family of reproducing kernel Hilbert spaces which interpolate between the Hardy space and the Fock space. We give characterizations of these spaces in terms of classical operators such as integration and…

Functional Analysis · Mathematics 2023-09-11 Daniel Alpay , Paula Cerejeiras , Uwe Kaehler , Baruch Schneider

We state and discuss several interrelated results, conjectures, and questions regarding contractive inequalities for classical $H^p$ spaces of the unit disc. We study both coefficient estimates in terms of weighted $\ell^2$ sums and the…

Functional Analysis · Mathematics 2018-12-05 Ole Fredrik Brevig , Joaquim Ortega-Cerdà , Kristian Seip , Jing Zhao

A set of reproducing kernel Hilbert spaces are obtained on Hilbert spaces over quaternion slices with the aid of coherent states. It is proved that the so obtained set forms a measurable field of Hilbert spaces and their direct integral…

Mathematical Physics · Physics 2016-09-30 K. Thirulogasanthar , B. Muraleetharan

This is an extended version of a three part mini course on the Drury-Arveson space given as part of the Focus Program on Analytic Function Spaces and their Applications, hosted by the Fields Institute and held remotely. The Drury-Arveson…

Functional Analysis · Mathematics 2022-04-05 Michael Hartz

Let $\mathbb H$ be the finite direct sums of $H^2(\mathbb D)$. In this paper, we give a characterization of the closed subspaces of $\mathbb H$ which are invariant under the shift, thus obtaining a concrete Beurling-type theorem for the…

Functional Analysis · Mathematics 2026-02-17 Filippo Bracci , Eva A. Gallardo-Gutiérrez

This paper considers paired operators in the context of the Lebesgue Hilbert space on the unit circle and its subspace, the Hardy space $H^2$. The kernels of such operators, together with their analytic projections, which are…

Functional Analysis · Mathematics 2024-02-09 M. Cristina Câmara , Jonathan R. Partington

We study the boundedness of composition operators on the bidisk using reproducing kernels. We show that a composition operator is bounded on the Hardy space of the bidisk if some associated function is a positive kernel. This positivity…

Complex Variables · Mathematics 2018-07-02 Cheng Chu

A class is studied of complex valued functions defined on the unit disk (with a possible exception of a discrete set) with the property that all their Pick matrices have not more than a prescribed number of negative eigenvalues. Functions…

Complex Variables · Mathematics 2007-05-23 V. Bolotnikov , A. Kheifets , L. Rodman

By applying methods of Duhamel algebra and reproducing kernels, we prove that every linear bounded operator on the Hardy-Hilbert space H^{2}(D) has a nontrivial invariant subspace. This solves affirmatively the Invariant Subspace Problem in…

Functional Analysis · Mathematics 2013-11-04 Mübariz Garayev

The Drury-Arveson space $H^2_d$, also known as symmetric Fock space or the $d$-shift space, is a Hilbert function space that has a natural $d$-tuple of operators acting on it, which gives it the structure of a Hilbert module. This survey…

Functional Analysis · Mathematics 2025-02-04 Michael Hartz , Orr Shalit

The category of Hilbert spaces and linear contractions is characterised by elementary categorical properties that do not refer to probabilities, complex numbers, norm, continuity, convexity, or dimension.

Category Theory · Mathematics 2025-02-04 Chris Heunen , Andre Kornell , Nesta van der Schaaf

By a famous result, functions in backward shift invariant subspaces in Hardy spaces are characterized by the fact that they admit a pseudocontinuation a.e. on $\T$. More can be said if the spectrum of the associated inner function has holes…

Complex Variables · Mathematics 2008-10-22 Andreas Hartmann

We characterize the de Branges-Rovnyak spaces with complete Nevanlinna-Pick property. Our method relies on the general theory of reproducing kernel Hilbert spaces.

Functional Analysis · Mathematics 2020-03-12 Cheng Chu

The Hilbert spaces are common. But the direct connection between them is rare. The aim of this paper is to establish a direct relation among the three Hilbert spaces Hardy, Bergman and Dirichlet without defining any of the Hilbert space in…

Functional Analysis · Mathematics 2021-10-22 Himanshu Singh

In the theory of complete Pick spaces, the column-row property has appeared in a variety of contexts. We show that it is satisfied by every complete Pick space in the following strong form: each sequence of multipliers that induces a…

Functional Analysis · Mathematics 2020-05-20 Michael Hartz

In this paper, we illustrate the effectiveness of reproducing kernel Hilbert space techniques in the study of composition operators. For weighted Hardy spaces on the unit disk, we characterize the composition operators whose adjoint is…

Functional Analysis · Mathematics 2026-01-28 Preeti Kumari , P. Muthukumar , Antti Rasila