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Related papers: Orthogonal polynomials in de Branges--Rovnyak spac…

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Given the reproducing kernel $k$ of the Hilbert space $\mathcal{H}_k$ we study spaces $\mathcal{H}_k(b)$ whose reproducing kernel has the form $k(1-bb^*)$, where $b$ is a row-contraction on $\mathcal{H}_k$. In terms of reproducing kernels…

Functional Analysis · Mathematics 2024-12-17 Alexandru Aleman , Frej Dahlin

Using an explicit construction, we show that the de Branges-Rovnyak spaces $\mathscr{H}(b)$, corresponding to rational $b$, are contained in their associated Smirnov classes.

Complex Variables · Mathematics 2022-02-15 Emmanuel Fricain , Andreas Hartmann , William T. Ross , Dan Timotin

In this paper we give an explicit description of de Branges-Rovnyak spaces $\HH(b)$ when $b$ is of the form $q^{r}$, where $q$ is a rational outer function in the closed unit ball of $H^{\infty}$ and $r$ is a positive number.

Complex Variables · Mathematics 2014-06-26 Emmanuel Fricain , Andreas Hartmann , William T. Ross

In this paper, we give an integral representation for the boundary values of derivatives of functions of the de Branges--Rovnyak spaces $\HH(b)$, where $b$ is in the unit ball of $H^\infty(\CC_+)$. In particular, we generalize a result of…

Complex Variables · Mathematics 2008-02-07 Emmanuel Fricain , Javad Mashreghi

In this paper, we characterize the boundedness and the compactness of weighted composition operators acting on a de Branges-Rovnyak space $\mathcal H(b)$, where the symbol $b$ is a rational function in the unit ball of $H^\infty$ that is…

Complex Variables · Mathematics 2025-12-18 Emmanuel Fricain , Muath Karaki , Javad Mashreghi , Maëva Ostermann

In this paper, we characterize the boundedness, the compactness and the Hilbert-Schmidt property for composition operators acting from a de Branges-Rovnyak space $\mathcal H(b)$ into itself, when $b$ is a rational function in the closed…

Functional Analysis · Mathematics 2022-11-10 Rim Alhajj , Emmanuel Fricain

In this paper we construct a large class of multiplication operators on reproducing kernel Hilbert spaces which are {\em homogeneous} with respect to the action of the M\"{o}bius group consisting of bi-holomorphic automorphisms of the unit…

Functional Analysis · Mathematics 2016-08-16 Adam Korányi , Gadadhar Misra

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

In most classical holomorphic function spaces on the unit disk, a function $f$ can be approximated in the norm of the space by its dilates $f\_r(z):=f(rz)~(r \textless{} 1)$. We show that this is \emph{not} the case for the de…

Functional Analysis · Mathematics 2015-01-14 O. El-Fallah , E. Fricain , K. Kellay , J. Mashreghi , Ransford Tom

For $S$ a contractive analytic operator-valued function on the unit disk ${\mathbb D}$, de Branges and Rovnyak associate a Hilbert space of analytic functions ${\mathcal H}(S)$ and related extension space ${\mathcal D(S)}$ consisting of…

Classical Analysis and ODEs · Mathematics 2014-05-14 Joseph A. Ball , Vladimir Bolotnikov

We study the orthogonal complement of the Hilbert subspace considered by by van Eijndhoven and Meyers in [J. Math. Anal. Appl. 146 (1990), no. 1, 89--98} and associated to holomorphic Hermite polynomials. A polyanalytic orthonormal basis is…

Classical Analysis and ODEs · Mathematics 2019-06-04 Abdelhadi Benahmadi , Allal Ghanmi , Mohammed Souid El Ainin

In most classical holomorphic function spaces on the unit disk in which the polynomials are dense, a function $f$ can be approximated in norm by its dilates $f_r(z):=f(rz)~(r<1)$, in other words, $\lim_{r\to1^-}\|f_r-f\|=0$. We construct a…

Complex Variables · Mathematics 2019-02-18 Javad Mashreghi , Thomas Ransford

We introduce \`a la Vasilevski the weighted poly-Bergman spaces in the unit disc and provide concrete orthonormal basis and give close expression of their reproducing kernel. The main tool in the description if these spaces is the so-called…

Complex Variables · Mathematics 2020-08-31 R. El Harti , A. ElKachkouri , A. Ghanmi

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

The aim of this paper is to characterize universal and multiplier interpolating sequences for de Branges-Rovnyak spaces H (b) where the defining function b is a general non-extreme rational function. Our results carry over to recently…

Complex Variables · Mathematics 2025-12-11 Andreas Hartmann , Giuseppe Lamberti

In this paper, we study the de Branges-Rovnyak spaces $\mathcal{H}(B)$ generated by row Schur functions $B$ with mate $a$. We prove that the polynomials are dense in $\mathcal{H}(B)$, and characterize the backward shift invariant subspaces…

Functional Analysis · Mathematics 2024-10-01 Hongxin Chen , Caixing Gu , Shuaibing Luo

Let R and S be two irreducible root systems spanning the same vector space and having the same Weyl group W, such that S (but not necessarily R) is reduced. For each such pair (R,S) we construct a family of W-invariant orthogonal…

Quantum Algebra · Mathematics 2007-05-23 Ian G. Macdonald

We obtain orthogonal decompositions for de Branges-Rovnyak spaces $\H\left( \tfrac {I^n(1+I)}{2}\right)$ and $\H\left( \tfrac {I(1+I^2)}{2}\right)$, where $I$ is an inner function. We also discuss the problem of cyclicity for these spaces.

Functional Analysis · Mathematics 2025-06-16 Łanucha Bartosz , Michalska Małgorzata , Nowak Maria

For $S$ a contractive analytic operator-valued function on the unit disk ${\mathbb D}$, de Branges and Rovnyak associate a Hilbert space of analytic functions ${\mathcal H}(S)$. A companion survey provides equivalent definitions and basic…

Classical Analysis and ODEs · Mathematics 2014-05-14 Joseph A. Ball , Vladimir Bolotnikov

We describe de Branges-Rovnyak spaces $\mathcal H (b_{\alpha})$, $\alpha>0$, where the function $b_{\alpha}$ is not extreme in the unit ball of $H^{\infty}$ on the unit disk $\mathbb D$, defined by the equality…

Functional Analysis · Mathematics 2018-07-13 Bartosz Łanucha , Maria T. Nowak
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