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We consider a Nevanlinna-Pick interpolation problem on finite sequences of the unit disc D constrained by Hardy and radial-weighted Bergman norms. We find sharp asymptotics on the corresponding interpolation constants. As another…

Complex Variables · Mathematics 2019-03-12 Anton Baranov , Rachid Zarouf

We study several aspects concerning slice regular functions mapping the quaternionic open unit ball into itself. We characterize these functions in terms of their Taylor coefficients at the origin and identify them as contractive…

Complex Variables · Mathematics 2013-08-13 Daniel Alpay , Vladimir Bolotnikov , Fabrizio Colombo , Irene Sabadini

We study noncommutative versions of holomorphic and harmonic functions on the unit disk.

Operator Algebras · Mathematics 2007-05-23 Slawomir Klimek

We provide an effective single-matrix criterion, in terms of what we call the elementary Pick matrix, for the solvability of the noncommutative Nevanlinna-Pick interpolation problem in the row ball, and provide some applications. In…

Functional Analysis · Mathematics 2020-05-18 Meric Augat , Michael T. Jury , James Eldred Pascoe

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

Given a domain $\Omega$ in $\mathbb{C}^m$, and a finite set of points $z_1,\ldots, z_n\in \Omega$ and $w_1,\ldots, w_n\in \mathbb{D}$ (the open unit disc in the complex plane), the $Pick\, interpolation\, problem$ asks when there is a…

Functional Analysis · Mathematics 2021-04-13 Tirthankar Bhattacharyya , Anindya Biswas , Vikramjeet Singh Chandel

We solve the commutant lifting and interpolation problems in the setting of the Hardy space and Schur functions on the open unit ball of $\mathbb{C}^n$. Our solutions also signify the role of inner functions on the unit ball, objects whose…

Complex Variables · Mathematics 2025-12-15 Jaydeep Bhattacharjee , Deepak K. D. , Jaydeb Sarkar

There are three new things in this paper about the open symmetrized bidisk $\mathbb G = \{(z_1+z_2, z_1z_2) : |z_1|, |z_2| < 1\}$. They are motivated in the Introduction. In this Abstract, we mention them in the order in which they will be…

Functional Analysis · Mathematics 2017-12-05 Tirthankar Bhattacharyya , Haripada Sau

It is very elementary to observe that functions interpolating an extremal two-point Pick problem on the polydisc are just left inverses to complex geodesics. In the present article we show that the same property holds for a three-point Pick…

Complex Variables · Mathematics 2015-03-12 Lukasz Kosinski

We introduce Nevanlinna classes of holomorphic functions associated to a closed set on the boundary of the unit disc in the complex plane and we get Blaschke type theorems relative to these classes by use of several complex variables…

Complex Variables · Mathematics 2017-06-14 Eric Amar

This article treats Nevanlinna-Pick interpolation in the setting of a special class of algebraic curves called distinguished varieties. An interpolation theorem, along with additional operator theoretic results, is given using a family of…

Functional Analysis · Mathematics 2013-02-06 Michael T. Jury , Greg Knese , Scott McCullough

In this article, we establish a connection between Pick bodies and invariant functions. We demonstrate that an invariant function can be associated with any Pick body, which determines the solvability of a given Pick interpolation problem…

Complex Variables · Mathematics 2025-02-17 Anindya Biswas

A Nevanlinna function is a function which is analytic in the open upper half plane and has a non-negative imaginary part there. In this paper we study a fractional linear transformation for a Nevanlinna function $n$ with a suitable…

Functional Analysis · Mathematics 2007-11-28 D. Alpay , A. Dijksma , H. Langer

We develop a theory of holomorphic functions in several noncommuting (free) variables and thus provide a framework for the study of arbitrary n-tuples of operators. The main topics are the following: Free holomorphic functions and Hausdorff…

Functional Analysis · Mathematics 2007-11-19 Gelu Popescu

We extend the study of the Pick class, the set of complex analytic functions taking the upper half plane into itself, to the noncommutative setting. R. Nevanlinna showed that elements of the Pick class have certain integral representations…

Functional Analysis · Mathematics 2013-10-18 J. E. Pascoe , Ryan Tully-Doyle

Under very general conditions it is shown that if $A$ is a uniform algebra generated by real-analytic functions, then either $A$ consists of all continuous functions or else there exists a disc on which every function in $A$ is holomorphic.…

Complex Variables · Mathematics 2017-10-10 Alexander J. Izzo

Bounded holomorphic interpolation problems associated to finitely many data have, in general, distinct solutions. Uniqueness arises only in some convex extreme configurations. Rational inner functions in a polydisk are the best understood…

Functional Analysis · Mathematics 2025-09-23 Mainak Bhowmik , Mihai Putinar

Nevanlinna-Pick interpolation developed from a topic in classical complex analysis to a useful tool for solving various problems in control theory and electrical engineering. Over the years many extensions of the original problem were…

Functional Analysis · Mathematics 2022-05-30 Sanne ter Horst , Alma van der Merwe

The main objects of study in this paper are those functionals that are analytic in the sense that they annihilate the non-commutative disc algebra. In the classical univariate case, a theorem of F. and M. Riesz implies that such functionals…

Operator Algebras · Mathematics 2021-04-07 Raphaël Clouâtre , Robert T. W. Martin , Edward J. Timko

We deal with a problem of the reconstruction of any holomorphic function $f$ on the unit ball of $\mathbb{C}^2$ from its restricions on a union of complex lines. We give an explicit formula of Lagrange interpolation's type that is…

Complex Variables · Mathematics 2008-03-31 Amadeo Irigoyen