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This paper considers paired operators in the context of the Lebesgue Hilbert space on the unit circle and its subspace, the Hardy space $H^2$. The kernels of such operators, together with their analytic projections, which are…

Functional Analysis · Mathematics 2024-02-09 M. Cristina Câmara , Jonathan R. Partington

Recently, it was shown that the image of a Toeplitz kernel of dimension greater than $1$ under composition by an inner function is nearly $S^*$-invariant if and only if the inner function is an automorphism. Building on this, we determine…

Functional Analysis · Mathematics 2025-10-08 Yuxia Liang , Jonathan R. Partington

The Rademacher series in rearrangement invariant function spaces "closed" to the space L_\infty are considered. In terms of interpolation theory of operators a correspondence between such spaces and spaces of coefficients generated by them…

Functional Analysis · Mathematics 2007-05-23 S. V. Astashkin

In this article we consider a class of integrable operators and investigate its connections with the following theories:the spectral theory of non-self-adjoint operators, the Riemann-Hilbert problem, the canonical differential systems and…

Functional Analysis · Mathematics 2007-05-23 Lev Sakhnovich

We review some classical and more recent results concerning kernels of Toeplitz operators and their relations with model spaces, which are themselves Toeplitz kernels of a special kind. We highlight the fundamental role played by the…

Functional Analysis · Mathematics 2017-11-28 M. Cristina Câmara , Jonathan R. Partington

We characterize matrix-valued asymmetric truncated Toeplitz operators (which are compressions of multiplication operators acting between two possibly different model spaces) by using compressed shifts, modified compressed shifts and shift…

Functional Analysis · Mathematics 2025-06-23 Rewayat Khan , Yagoub Ameur , Jamroz Khan

Compressions of Toeplitz operators to coinvariant subspaces of $H^2$ are called truncated Toeplitz operators. We study two questions related to these operators. The first, raised by Sarason, is whether boundedness of the operator implies…

Functional Analysis · Mathematics 2009-11-14 A. Baranov , Isabelle Chalendar , Emmanuel Fricain , Javad Mashreghi , Dan Timotin

Let $T$ be an absolutely continuous polynomially bounded operator, and let $\theta$ be a singular inner function. It is shown that if $\theta(T)$ is invertible and some additional conditions are fulfilled, then $T$ has nontrivial…

Functional Analysis · Mathematics 2019-12-17 Maria F. Gamal'

This paper is about the operators defined between K\"othe spaces whose associated matrix is a Hankel matrix. After demonstrating how these operators are defined, the conditions for continuity and compactness of these operators are…

Functional Analysis · Mathematics 2024-10-01 Nazlı Doğan

Prony's problem in several variables has attracted some attention recently and provides an interesting combination of polynomial ideal theory with analytic and numeric computations. This note points out further connections to Hankel…

Numerical Analysis · Mathematics 2018-05-23 Tomas Sauer

This survey on approximations of perturbed operator functions addresses recent advances and some of the successful methods.

Functional Analysis · Mathematics 2013-03-01 Anna Skripka

We study the intertwining relations between analytic Toeplitz operators induced on the Hardy space H^2 by analytic functions bounded on the open unit disc. Our work centers on the connection between intertwining between the Toeplitz…

Functional Analysis · Mathematics 2009-03-31 Paul S. Bourdon , Joel H. Shapiro

Generalized Toeplitz plus Hankel operators $T(a)+H_{\alpha}(b)$ generated by functions $a,b$ and a linear fractional Carleman shift $\alpha$ changing the orientation of the unit circle $\mathbb{T}$ are considered on the Hardy spaces…

Functional Analysis · Mathematics 2015-01-20 Victor D. Didenko , Bernd Silbermann

This paper is a survey on the emerging theory of truncated Toeplitz operators. We begin with a brief introduction to the subject and then highlight the many recent developments in the field since Sarason's seminal paper in 2007.

Complex Variables · Mathematics 2012-06-25 Stephan Ramon Garcia , William T. Ross

There is a resent paper claiming that every hyponormal operator which is not a multiple of the identity (operator) has a nontrivial hyperinvariant subspace. If this claim is true, then every hyponormal operator has a nontrivial invariant…

Functional Analysis · Mathematics 2024-01-30 Junfeng Liu

The theory of Toeplitz quantization presented in our previous paper is extended and further developed to include diverse and interesting non-commutative realizations of the classical Euclidean plane. This is done using Hilbert spaces of…

Quantum Physics · Physics 2021-05-19 Micho Durdevich , Stephen Bruce Sontz

The basic results for nonlinear operators are given. These results include nonlinear versions of classical uniform boundedness theorem and Hahn-Banach theorem. Furthermore, the mappings from a metrizable space into another normed space can…

Functional Analysis · Mathematics 2019-05-28 Wen Hsiang Wei

We investigate truncated Toeplitz operators belonging to the Schatten ideals. We completely characterize such operators when they have an analytic symbol or belong to the ideal of Hilbert-Schmidt operators. We also study model spaces…

Complex Variables · Mathematics 2014-10-09 Patrick Lopatto , Richard Rochberg

To a pair of subspaces wandering with respect to a row isometry we associate a transfer function which in general is multi-Toeplitz and in interesting special cases is multi-analytic. Then we describe in an expository way how characteristic…

Functional Analysis · Mathematics 2012-06-05 Rolf Gohm

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