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Given a finite set \sigma of the unit disc \mathbb{D}={z\in\mathbb{C}:, |z|<1} and a holomorphic function f in \mathbb{D} which belongs to a class X, we are looking for a function g in another class Y (smaller than X) which minimizes the…

Functional Analysis · Mathematics 2012-12-04 Rachid Zarouf

For a bounded analytic function $\varphi$ on the unit disk $\D$ with $\|\varphi\|_\infty\le1$ we consider the defect operators $D_\varphi$ and $D_{\overline\varphi}$ of the Toeplitz operators $T_\varphi$ and $T_{\overline\varphi}$,…

Complex Variables · Mathematics 2024-11-20 Shuaibing Luo , Kehe Zhu

The theory of Nevanlinna-Pick and Carath\'eodory-Fej\'er interpolation for matrix- and operator-valued Schur class functions on the unit disk is now well established. Recent work has produced extensions of the theory to a variety of…

Functional Analysis · Mathematics 2008-08-19 J. A. Ball , S. ter Horst

We extend our Nevanlinna-Pick theorem for Hardy algebras and their representations to cover interpolation at the absolutely continuous points of the boundaries of their discs of representations. The Lyapunov order plays a crucial role in…

Operator Algebras · Mathematics 2011-07-05 Paul S. Muhly , Baruch Solel

This note finds a new characterization of complete Nevanlinna-Pick kernels on the Euclidean unit ball. The classical theory of Sz.-Nagy and Foias about the characteristic function is extended in this note to a commuting tuple $\bfT$ of…

Functional Analysis · Mathematics 2023-05-01 Tirthankar Bhattacharyya , Abhay Jindal

In this paper we give precise characterizations of the relation between the Nevanlinna counting function and pull-back measure of an analytic self-map of the unit disk near the boundary. We show that it is quite worth considering these two…

Functional Analysis · Mathematics 2022-04-29 Yong-Xin Gao , Yuxia Liang , Ze-Hua Zhou

This paper concerns a commutant lifting theorem and a Nevanlinna-Pick type interpolation result in the setting of multipliers from vector-valued Drury-Arveson space to a large class of vector-valued reproducing kernel Hilbert spaces over…

Functional Analysis · Mathematics 2019-12-04 Deepak K. D. , Deepak Pradhan , Jaydeb Sarkar , Dan Timotin

Let $\Omega$ be a Cartan domain and $K = \sum_{\underline s}a_{\underline s}K_{\underline s}$ be a $\mathbb K$-invariant kernel on $\Omega$. In this article, we first obtain a necessary condition on $K$ to have the complete Nevanlinna-Pick…

Functional Analysis · Mathematics 2026-03-06 Miroslav Engliš , Somnath Hazra , Paramita Pramanick

We solve a three point Nevanlinna-Pick problem in the Euclidean ball. In particular, we determine a class of rational functions that interpolate this problem.

Complex Variables · Mathematics 2016-04-14 Łukasz Kosiński , Włodzimierz Zwonek

We introduce Nevanlinna--Pick norms associated with finite families of characters in a commutative semisimple Banach algebra and study the class $NP_\infty$, where all such norms are minimal. Our main result is a topological rigidity…

Functional Analysis · Mathematics 2026-05-12 Przemysław Ohrysko , Michał Wojciechowski

We prove a factorization theorem for reproducing kernel Hilbert spaces whose kernel has a normalized complete Nevanlinna-Pick factor. This result relates the functions in the original space to pointwise multipliers determined by the…

Functional Analysis · Mathematics 2018-07-19 Alexandru Aleman , Michael Hartz , John E. McCarthy , Stefan Richter

Given a finite set \sigma of the unit disc \mathbb{D}=\{z\in\mathbb{C}:,\,| z|<1\} and a holomorphic function f in \mathbb{D} which belongs to a class X, we are looking for a function g in another class Y (smaller than X) which minimizes…

Functional Analysis · Mathematics 2011-03-28 Rachid Zarouf

In \cite{ds_hfs}, a geometric procedure for constructing a Nevanlinna-Pick problem on $\D^n$ with a specified set of uniqueness was established. In this sequel we conjecture a necessary and a sufficient condition for a Nevanlinna-Pick…

Complex Variables · Mathematics 2013-02-22 David Scheinker

Let $\mathcal H$ be the Drury-Arveson or Dirichlet space of the unit ball of $\mathbb C^d$. The weak product $\mathcal H\odot\mathcal H$ of $\mathcal H$ is the collection of all functions $h$ that can be written as $h=\sum_{n=1}^\infty f_n…

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

We study reproducing kernel Hilbert spaces on the unit ball with the complete Nevanlinna-Pick property through the representation theory of their algebras of multipliers. We give a complete description of the representations in terms of the…

Operator Algebras · Mathematics 2020-09-23 Raphaël Clouâtre , Michael Hartz

In the paper `Distinguished Varieties,' Agler and McCarthy used Hilbert function spaces to study the uniqueness properties of the Nevanlinna-Pick problem on the bidisc. In this work we give a geometric procedure for constructing a…

Functional Analysis · Mathematics 2011-05-04 David Scheinker

This paper studies the determining sets for analytic functions from the symmetrized bidisk into the open unit disk in $\mathbb C$. It relates the idea to the uniqueness of the solutions of a Nevanlinna-Pick interpolation problem. It also…

Complex Variables · Mathematics 2022-08-15 B. Krishna Das , P. Kumar , H. Sau

Given a sequence of points in the unit disk, a well known result due to Carleson states that if given any point of the sequence it is possible to interpolate the value one in that point and zero in all the other points of the sequence, with…

Complex Variables · Mathematics 2013-02-05 Andreas Hartmann

General results of interpolation (eg. Nevanlinna-Pick) by elements in the noncommutative analytic Toeplitz algebra $F^\infty$ (resp. noncommutative disc algebra $A_n$) with consequences to the interpolation by bounded operator-valued…

Functional Analysis · Mathematics 2016-09-07 Alvaro Arias , Gelu Popescu

A boundary Nevanlinna-Pick interpolation problem is posed and solved in the quaternionic setting. Given nonnegative real numbers $\kappa_1, \ldots, \kappa_N$, quaternions $p_1, \ldots, p_N$ all of modulus $1$, so that the $2$-spheres…

Complex Variables · Mathematics 2014-05-27 K. Abu-Ghanem , D. Alpay , F. Colombo , D. P. Kimsey , I. Sabadini