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The techniques developed by Popescu, Muhly-Solel and Good for the study of algebras generated by weighted shifts are applied to generalize results of Sarkar and of Bhattacharjee-Eschmeier-Keshari-Sarkar concerning dilations and invariant…

Functional Analysis · Mathematics 2020-03-10 Baruch Solel

We introduce connections between the Cuntz relations and the Hardy space H_2 of the open unit disk . We then use them to solve a new kind of multipoint interpolation problem in H_2, where for instance, only a linear combination of the…

Functional Analysis · Mathematics 2013-01-21 Daniel Alpay , Palle Jorgensen , Izchak Lewkowicz , Itzik Martziano

The symmetrized bidisc has been a rich field of holomorphic function theory and operator theory. A certain well-known reproducing kernel Hilbert space of holomorphic functions on the symmetrized bidisc resembles the Hardy space of the unit…

Functional Analysis · Mathematics 2020-03-23 Tirthankar Bhattacharyya , B. Krishna Das , Haripada Sau

A representation theorem for non-semibounded Hermitian quadratic forms in terms of a (non-semibounded) self-adjoint operator is proven. The main assumptions are closability of the Hermitian quadratic form, the direct integral structure of…

Functional Analysis · Mathematics 2022-07-11 Alberto Ibort , José G. Llavona , Fernando Lledó , Juan Manuel Pérez-Pardo

We show how quiver representations and their invariant theory natu- rally arise in the study of some moduli spaces parametrizing bundles dened on an algebraic curve, and how they lead to ne results regarding the geometry of these spaces.

Representation Theory · Mathematics 2009-12-17 Olivier Serman

We describe the proper closed invariant subspaces of the integration operator when it acts continuously on countable intersections and countable unions of weighted Banach spaces of holomorphic functions on the unit disc or the complex…

Functional Analysis · Mathematics 2020-04-07 José Bonet , Antonio Galbis

A commuting $n$-tuple $(T_1, \ldots, T_n)$ of bounded linear operators on a Hilbert space $\clh$ associate a Hilbert module $\mathcal{H}$ over $\mathbb{C}[z_1, \ldots, z_n]$ in the following sense: \[\mathbb{C}[z_1, \ldots, z_n] \times…

Functional Analysis · Mathematics 2014-09-30 Jaydeb Sarkar

We develop a theory of Valuation Hilbert Modules and prove a version of Beurling's theorem for these. Then we apply our version of Beurling's theorem to obtain complete descriptions of the closed invariant subspaces of a number of Hilbert…

Complex Variables · Mathematics 2023-06-23 Charles W. Neville

We consider hilbert spaces of holomorphic functions in Cartan domains (in particular in ball and polydisk) and operator of restriction of holomorphic function to a submanifold in Shilov boundary. We discuss conditions when this operator…

funct-an · Mathematics 2013-01-15 Yurii A. Neretin

A regular generalized sampling theory in some structured T-invariant subspaces of a Hilbert space H, where T denotes a bounded invertible operator in H, is established in this paper. This is done by walking through the most important cases…

Functional Analysis · Mathematics 2018-04-10 Antonio G. García , María J. Muñoz-Bouzo , Gerardo Pérez-Villalón

Let $T\in B(\mathcal{H})$ be an invertible operator. From the 1940's, Gelfand, Hille and Wermer investigated the invariant subspaces of $T$ by analyzing the growth of $\|T^n\|$, where $n\in \mathbb{Z}$. In this paper, we study the invariant…

Functional Analysis · Mathematics 2025-06-19 Junsheng Fang , Bingzhe Hou , Chunlan Jiang , Yuanhang Zhang

In this paper we consider the reproducing kernel thesis for boundedness and compactness for operators on $\ell^2$--valued Bergman-type spaces. This paper generalizes many well--known results about classical function spaces to their…

Classical Analysis and ODEs · Mathematics 2015-05-21 Robert Rahm

In view of recent developments of the study of reproducing kernel Hilbert spaces, in particular with the context the Hardy spaces on tubes, aspects of rational approximation for functions of finite energy in several complex and several real…

Complex Variables · Mathematics 2020-02-26 Weixiong Mai , Tao Qian

In this paper, we study vector valued de Branges spaces associated with a de Branges operator, defined as a pair of Fredholm operator valued analytic functions on a domain symmetric with respect to the unit circle. Using a suitable direct…

Functional Analysis · Mathematics 2026-04-14 Bharti Garg , Santanu Sarkar

New obstructions for embedding one compact oriented 3-manifold in another are given. A theorem of D. Krebes concerning 4-tangles embedded in links arises as a special case. Algebraic and skein-theoretic generalizations for 2n-tangles…

Geometric Topology · Mathematics 2009-11-10 Jozef H. Przytycki , Daniel S. Silver , Susan G. Williams

In this paper we study some basic properties of bicomplex linear operators on bicomplex Hilbert spaces. Further we discuss some applications of Hahn-Banach theorem on bicomplex Banach modules. We also introduce and discuss some bicomplex…

Functional Analysis · Mathematics 2014-06-02 Romesh Kumar , Kulbir Singh

The objective of this article is to study nearly invariant subspaces of the backward shift operator on the real Hardy space. We also investigate nearly invariant subspaces with finite defect, and as a consequence, provide a characterization…

Functional Analysis · Mathematics 2026-04-14 Arshad Khan , Sneh Lata , Dinesh Singh

We reconsider studies of Toeplitz operators on function spaces (the weighted Bergman space, the generalized derivative Hardy space) and the H-Toeplitz operators on the Bergman space. Past studies have considered the presence or absence of…

Functional Analysis · Mathematics 2024-09-20 Chafiq Benhida , George R. Exner , Ji Eun Lee , Jongrak Lee

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

We reorganize, simplify and expand the theory of contractions or interior products of multivectors, and related topics like Hodge star duality. Many results are generalized and new ones are given, like: geometric characterizations of blade…

General Mathematics · Mathematics 2024-10-30 André L. G. Mandolesi