Bartosz Malman

activity

20172026

most citedHilbert spaces of analytic functions with a contractive backward shift

20 citations · 21 across the 22 of their papers we have counts for

collaborators

24 papers

math.CA2026

Uniqueness sets in weighted $ℓ^{2}$ -spaces via simultaneous approximation

Linus Bergqvist, Adem Limani, Bartosz Malman

We consider a family of uniqueness problems in the setting of weighted $ℓ^{2}$ Fourier spaces on the unit-circle, from the perspective of simultaneous approximation. We develop a…

math.FA2026

Tangential boundary behavior in Hilbert spaces of analytic functions

Shuaibing Luo, Bartosz Malman

Sarason's Hilbert space version of Carathéodory-Julia Theorem connects the non-tangential boundary behavior of functions in de Branges-Rovnyak space $H (b)$ with the existence of an…

math.CV2025

A critical majorant for the Khinchin-Ostrowski property

Bartosz Malman

In this short note we prove an optimal version of a classical result. Given a majorant determining a growth restriction on functions in the unit disk $D$ , we say that a se…

math.CV2025

Revisiting cyclic elements in growth spaces

Linus Bergqvist, Adem Limani, Bartosz Malman

We revisit the problem of characterizing cyclic elements for the shift operator in a broad class of radial growth spaces of holomorphic functions on the unit disk, focusing on func…

math.CV2025

Weighted Korenblum-Roberts Theory

Bartosz Malman

The classical Korenblum-Roberts Theorem characterizes the cyclic singular inner functions in the Bergman spaces of the unit disk $D$ as those for which the corresponding s…

math.FA2024

Universal multipliers for Sub-Hardy Hilbert spaces

Bartosz Malman, Daniel Seco

To every non-extreme point $b$ of the unit ball of $\hil^\infty$ of the unit disk there corresponds a Pythagorean mate, a bounded outer function $a$ satisfying the equation $|a|^2…

math.FA2024

On the Crouzeix ratio for $N \times N$ matrices

Bartosz Malman, Javad Mashreghi, Ryan O'Loughlin +1

The Crouzeix ratio $ψ (A)$ of an $N \times N$ complex matrix $A$ is the supremum of $∥ p (A) ∥$ taken over all polynomials $p$ such that $∣ p ∣ \leq 1$ on the numerical range of $A$ . It i…

math.CA2024

Distributing mass under a pointwise bound and an application to weighted polynomial approximation

Linus Bergqvist, Bartosz Malman

Inspired by applications in weighted polynomial approximation problems, we study an optimal mass distribution problem. Given a gauge function $h$ and a positive "roof" function $R$ …

math.FA2024

Double-layer potentials, configuration constants and applications to numerical ranges

Bartosz Malman, Javad Mashreghi, Ryan O'Loughlin +1

Given a compact convex planar domain $Ω$ with non-empty interior, the classical Neumann's configuration constant $c_{R} (Ω)$ is the norm of the Neumann-Poincaré operator $K…

math.CV2024

Embeddings into de Branges-Rovnyak spaces

Bartosz Malman, Daniel Seco

We study conditions for containment of a given space $X$ of analytic functions on the unit disk $D$ in the de Branges-Rovnyak space $H (b)$ . We deal with the non-…

math.CV2023

Spectral clumping for functions decreasing rapidly on a half-line

Bartosz Malman

We demonstrate a phenomenon of condensation of the Fourier transform $f$ of a function $f$ defined on the real line $R$ which decreases rapidly on one half of th…

math.CV2023

Shift operators, Cauchy integrals and approximations

Bartosz Malman

This article consists of two connected parts. In the first part, we study the shift invariant subspaces in certain $P^{2} (μ)$ -spaces, which are the closures of analytic pol…

math.FA2023

Revisiting mean-square approximation by polynomials in the unit disk

Bartosz Malman

For a positive finite Borel measure $μ$ compactly supported in the complex plane, the space $P^{2} (μ)$ is the closure of the analytic polynomials in the Lebesgue space $L^2…

math.FA2022

Thomson decompositions of measures in the disk

Bartosz Malman

We study the classical problem of identifying the structure of $P^{2} (μ)$ , the closure of analytic polynomials in the Lebesgue space $L^{2} (μ)$ of a compactly supported Borel measure $…

math.CV2022

Cyclic inner functions in growth classes and applications to approximation problems

Bartosz Malman

It is well-known that for any inner function $θ$ defined in the unit disk $D$ the following two conditons: $(i)$ there exists a sequence of polynomials ${p_{n}}_{n}$ such that $\lim_…

math.FA2021

Constructions of some families of smooth Cauchy transforms

Adem Limani, Bartosz Malman

For a given Beurling-Carleson subset $E$ of the unit circle $T$ which has positive Lebesgue measure, we give explicit formulas for measurable functions supported on $E$ su…

math.FA2021

Inner functions, invariant subspaces and cyclicity in $P^{t} (μ)$ -spaces

Adem Limani, Bartosz Malman

We study the invariant subspaces generated by inner functions for a class of $P^{t} (μ)$ -spaces which can be identified as spaces of analytic functions in the unit disk $\ma…

math.FA2021★ 1 cited

On the problem of smooth approximations in de Branges-Rovnyak spaces and connections to subnormal operators

Adem Limani, Bartosz Malman

For the class of de Branges-Rovnyak spaces $H (b)$ of the unit disk $D$ defined by extreme points $b$ of the unit ball of $H^{\infty}$ , we study the problem of appr…

math.FA2021

An abstract approach to approximations in spaces of pseudocontinuable functions

Adem Limani, Bartosz Malman

We give an abstract approach to approximations with a wide range of regularity classes $X$ in spaces of pseudocontinuable functions $K_{ϑ}^{p}$ , where $ϑ$ is an inner f…

math.FA2021

On model spaces and density of functions smooth on the boundary

Adem Limani, Bartosz Malman

We characterize the model spaces $K_{Θ}$ in which functions with smooth boundary extensions are dense. It is shown that such approximations are possible if and only if the singular m…

math.FA2019

Generalized Cesàro operators: geometry of spectra and quasi-nilpotency

Adem Limani, Bartosz Malman

For the class of Hardy spaces and standard weighted Bergman spaces of the unit disk we prove that the spectrum of a generalized Cesàro operator $T_{g}$ is unchanged if the symbol $g$ …

math.FA2019

Nearly invariant subspaces of de Branges spaces

Bartosz Malman

We prove that the nearly invariant subspaces of a de Branges space which have no common zeros are precisely of the form an exponential function times a de Branges space.

math.FA2018★ 20 cited

Hilbert spaces of analytic functions with a contractive backward shift

Alexandru Aleman, Bartosz Malman

We consider Hilbert spaces of analytic functions in the disk with a normalized reproducing kernel and such that the backward shift $f (z) \mapsto \frac{f ( z ) - f ( 0 )}{z}$ is a contracti…

math.FA2017

Density of disc algebra functions in de Branges-Rovnyak spaces

Alexandru Aleman, Bartosz Malman

We prove that functions continuous up to the boundary are dense in de Branges-Rovnyak spaces induced by extreme points the unit ball of $H^{\infty}$ .

Uniqueness sets in weighted ℓ2-spaces via simultaneous approximation

Tangential boundary behavior in Hilbert spaces of analytic functions

A critical majorant for the Khinchin-Ostrowski property

Revisiting cyclic elements in growth spaces

Weighted Korenblum-Roberts Theory

Universal multipliers for Sub-Hardy Hilbert spaces

On the Crouzeix ratio for N×N matrices

Distributing mass under a pointwise bound and an application to weighted polynomial approximation

Double-layer potentials, configuration constants and applications to numerical ranges

Embeddings into de Branges-Rovnyak spaces

Spectral clumping for functions decreasing rapidly on a half-line

Shift operators, Cauchy integrals and approximations

Revisiting mean-square approximation by polynomials in the unit disk

Thomson decompositions of measures in the disk

Cyclic inner functions in growth classes and applications to approximation problems

Constructions of some families of smooth Cauchy transforms

Inner functions, invariant subspaces and cyclicity in Pt(μ)-spaces

On the problem of smooth approximations in de Branges-Rovnyak spaces and connections to subnormal operators

An abstract approach to approximations in spaces of pseudocontinuable functions

On model spaces and density of functions smooth on the boundary

Generalized Cesàro operators: geometry of spectra and quasi-nilpotency

Nearly invariant subspaces of de Branges spaces

Hilbert spaces of analytic functions with a contractive backward shift

Density of disc algebra functions in de Branges-Rovnyak spaces

Uniqueness sets in weighted $ℓ^{2}$ -spaces via simultaneous approximation

On the Crouzeix ratio for $N \times N$ matrices

Inner functions, invariant subspaces and cyclicity in $P^{t} (μ)$ -spaces