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In this paper we are concerned with hyponormality and subnormality of block Toeplitz operators acting on the vector-valued Hardy space $H^2_{\mathbb{C}^n}$ of the unit circle. Firstly, we establish a tractable and explicit criterion on the…

Functional Analysis · Mathematics 2012-07-16 Raul Curto , In Sung Hwang , Woo Young Lee

Let $\Omega\subset \mathbb{C}^2$ be a bounded convex domain with $C^1$-smooth boundary and $\varphi\in C^1(\overline{\Omega})$ such that $\varphi$ is harmonic on the nontrivial disks in the boundary. We estimate the essential norm of the…

Complex Variables · Mathematics 2021-03-08 Zeljko Cuckovic , Sonmez Sahutoglu

In this paper, we completely characterize when two dual truncated Toeplitz operators are essentially commuting and when the semicommutator of two dual truncated Toeplitz operators is compact. Our main idea is to study dual truncated…

Functional Analysis · Mathematics 2020-12-29 Chongchao Wang , Xianfeng Zhao , Dechao Zheng

In this survey we show how to produce asymptotics of determinants of structured matrices using operator theory methods. We describe the asymptotics for finite Toeplitz matrices, finite Toeplitz plus Hankel matrices and generalizations of…

Functional Analysis · Mathematics 2024-08-01 E. Basor , T. Ehrhardt , J. A. Virtanen

An estimate for the norm of selfadjoint Toeplitz operators with a radial, bounded and integrable symbol is obtained. This emphasizes the fact that the norm of such operator is strictly less than the supremum norm of the symbol. Consequences…

Functional Analysis · Mathematics 2021-02-04 Antonio Galbis

As a class of compact operators on the $\ell^2-$valued Bergman space $A^2_\alpha (\mathbb B_n, \ell^2)$ on the unit ball $\mathbb B_n,$ we study Toeplitz operators with $BMO^1_\alpha (\mathbb B_n, \mathcal L(\ell^2))$ operator-valued…

Classical Analysis and ODEs · Mathematics 2025-10-23 David Békollè , Hugues Olivier Défo , Edgar L. Tchoundja

This paper studies the \(k^{th}-\)order slant Toeplitz and slant little Hankel operators on the weighted Bergman space \(\mathcal{A}_\alpha^2(\mathbb{D})\). These operators are constructed using a slant shift operator \(W_k\) composed with…

Functional Analysis · Mathematics 2025-07-10 Oinam Nilbir Singh , M. P. Singh , Thokchom Sonamani Singh

We find a concrete integral formula for the class of generalized Toeplitz operators $T_a$ in Bergman spaces $A^p$, $1<p<\infty$, studied in an earlier work by the authors. The result is extended to little Hankel operators. We give an…

Functional Analysis · Mathematics 2017-03-30 Jari Taskinen , Jani Virtanen

We consider Toeplitz operators with bounded symbol acting on the Bergman space of the unit disk and assess their hyponormality. We will mainly be concerned with the symbol $\varphi(z)=z^{n}|z|^{2s}+a(t)\bar{z}^{m}|z|^{2t}$, where $s$ and…

Classical Analysis and ODEs · Mathematics 2025-03-06 Nicole Revilla , Brian Simanek

We consider kernels of unbounded Toeplitz operators in $H^p(\mathbb C^+)$ in terms of a factorization of their symbols. We study the existence of a minimal Toeplitz kernel containing a given function in $H^p(\mathbb C^+)$, we describe the…

Functional Analysis · Mathematics 2020-04-22 M. Cristina Câmara , M. Teresa Malheiro , Jonathan R. Partington

We define and study Toeplitz operators in the space of Herglotz solutions of the Helmholtz equation in $R^d$. As the most traditional definition of Toeplitz operators via Bergman-type projection is not available here, we use an approach…

Functional Analysis · Mathematics 2016-05-24 Grigori Rozenblum , Nikolai Vasilevski

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

The notion of slant H-Toeplitz operator $V_\phi$ on the Hardy space $H^2$ is introduced and its characterizations are obtained. We have shown that an operator on the space $H^2$ is slant H-Toeplitz if and only if its matrix is a slant…

Functional Analysis · Mathematics 2018-01-15 Anuradha Gupta , Shivam Kumar Singh

We explore the optimality of the constants making valid the recently established Little Grothendieck inequality for JB$^*$-triples and JB$^*$-algebras. In our main result we prove that for each bounded linear operator $T$ from a…

Operator Algebras · Mathematics 2022-04-25 Ondřej F. K. Kalenda , Antonio M. Peralta , Hermann Pfitzner

In the semiclassical limit, it is well-known that the first eigenvector of a Toeplitz operator concentrates on the minimal set of the symbol. In this paper, we give a more precise criterion for concentration in the case where the minimal…

Spectral Theory · Mathematics 2018-03-08 Alix Deleporte

A major open problem in the Theory of Toeplitz operators on the analytic Bergman space over the unit disk is the characterization of the commutant of a given Toeplitz operator--that is, the set of all bounded Toeplitz operators that commute…

Functional Analysis · Mathematics 2025-03-19 Aissa Bouhali , Issam Louhichi , Abdel Rahman Yousef

We solve the following problems associated with Toeplitz operators $T_{\Phi}$ on Hilbert space-valued Hardy spaces $H_{\mathcal{E}}^2(\mathbb{D}^n)$ over the unit polydisc $\mathbb{D}^n$. $(I)$ Given operator-valued bounded analytic…

Functional Analysis · Mathematics 2025-06-04 Srijan Sarkar

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

Given a stable SISO LTI system $G$, we investigate the problem of estimating the $\mathcal{H}_\infty$-norm of $G$, denoted $||G||_\infty$, when $G$ is only accessible via noisy observations. Wahlberg et al. recently proposed a nonparametric…

Optimization and Control · Mathematics 2017-10-02 Stephen Tu , Ross Boczar , Benjamin Recht

In this paper we study operators of the form $M(\phi)=T(\phi)+H(\phi)$ where $T(\phi)$ and $H(\phi)$ are the Toeplitz and Hankel operators acting on $H^p(\T)$ with generating function $\phi\in L^\iy(\T)$. It turns out that $M(\phi)$ is…

Functional Analysis · Mathematics 2007-05-23 Estelle Basor , Torsten Ehrhardt