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Related papers: The weighted Hilbert--Schmidt numerical radius

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In this paper, we generalize the notions of numerical radius parallelism and numerical radius Birkhoff orthogonality, originally formulated for operators on Hilbert spaces, to operators on normed spaces. We then proceed to demonstrate their…

Functional Analysis · Mathematics 2024-12-03 Jiaye Bi , Huayou Xie , Yongjin Li

For $n$-by-$n$ and $m$-by-$m$ complex matrices $A$ and $B$, it is known that the inequality $w(A\otimes B)\le\|A\|w(B)$ holds, where $w(\cdot)$ and $\|\cdot\|$ denote, respectively, the numerical radius and the operator norm of a matrix. In…

Functional Analysis · Mathematics 2013-10-22 Hwa-Long Gau , Kuo-Zhong Wang , Pei Yuan Wu

This paper presents a study of the generalized Davis-Wielandt radius of Hilbert space operators. New lower bounds for the generalized Davis-Wielandt radius and numerical radius are provided. An alternative of the triangular inequality for…

Functional Analysis · Mathematics 2026-03-05 Mehdi Naimi , Mohammed Benharrat , Faouzi Hireche

We establish new upper bounds for Berezin number and Berezin norm of operator matrices, which are refinements of the existing bounds. Among other bounds, we prove that if $A=[A_{ij}]$ is an $n\times n$ operator matrix with…

Functional Analysis · Mathematics 2024-08-14 Pintu Bhunia , Anirban Sen , Somdatta Barik , Kallol Paul

Regularity estimates for an integral operator with a symmetric continuous kernel on a convex bounded domain are derived. The covariance of a mean-square continuous random field on the domain is an example of such an operator. The estimates…

Probability · Mathematics 2022-04-25 Mihály Kovács , Annika Lang , Andreas Petersson

In this paper, we give the Alzer inequality for Hilbert space operators as follows: Let $A, B$ be two selfadjoint operators on a Hilbert space $\mathcal H$ such that $0 < A, B \le \frac{1}{2}I$, where $I$ is identity operator on $\mathcal…

Functional Analysis · Mathematics 2018-06-29 Ali Morassaei , Farzollah Mirzapour

Let $H$ be a reflexive, dense, separable, infinite dimensional complex Hilbert space and let $B(H)$ be the algebra of all bounded linear operators on $H$. In this paper, we carry out characterizations of norm-attainable operators in normed…

Functional Analysis · Mathematics 2020-04-14 Benard Okelo

We compute the exact value of the essential norm of a generalized Hilbert matrix operator acting on weighted Bergman spaces $A^p_v$ and weighted Banach spaces $H^\infty_v$ of analytic functions, where $v$ is a general radial weight. In…

Functional Analysis · Mathematics 2022-01-25 Mikael Lindström , Santeri Miihkinen , David Norrbo

Let $\mathcal{H}$ be a Hilbert space, $L(\mathcal{H})$ the algebra of bounded linear operators on $\mathcal{H}$ and $W \in L(\mathcal{H})$ a positive operator such that $W^{1/2}$ is in the p-Schatten class, for some $1 \leq p< \infty.$…

Functional Analysis · Mathematics 2016-10-04 Maximiliano Contino , Juan Giribet , Alejandra Maestripieri

This article implements a simple convex approach and block techniques to obtain several new refined versions of numerical radius inequalities for Hilbert space operators. This includes comparisons among the norms of the operators, their…

Functional Analysis · Mathematics 2023-02-15 Mohammad Sababheh , Cristian Conde , Hamid Reza Moradi

We investigate $\rho$-orthogonality and its local symmetry in the space of bounded linear operators. A characterization of Hilbert space operators with symmetric numerical range is established in terms of $\rho$-orthogonality. Further, we…

Functional Analysis · Mathematics 2025-12-15 Souvik Ghosh , Kallol Paul , Debmalya Sain

In this article, a series of new inequalities involving the $q$-numerical radius for $n\times n$ tridiagonal, and anti-tridiagonal operator matrices has been established. These inequalities serve to establish both lower and upper bounds for…

Functional Analysis · Mathematics 2025-01-14 Satyajit Sahoo , Narayan Behera

Let $\mathbf{T}=(T_1,\ldots,T_d)$ be a $d$-tuple of operators on a complex Hilbert space $\mathcal{H}$. The spherical Aluthge transform of $\mathbf{T}$ is the $d$-tuple given by…

Functional Analysis · Mathematics 2020-04-07 Kais Feki , Takeaki Yamazaki

We study a specific family of symmetric norms on the algebra $\mathcal B(\mathcal H)$ of operators on a separable infinite-dimensional Hilbert space. With respect to each symmetric norm in this family the identity operator fails to attain…

Functional Analysis · Mathematics 2020-09-24 Satish K. Pandey

Relatively recently, K.M.R. Audenaert (2010), R.A. Horn and F. Zhang (2010), Z. Huang (2011), A.R. Schep (2011), A. Peperko (2012), D. Chen and Y. Zhang (2015) have proved inequalities on the spectral radius and the operator norm of…

Functional Analysis · Mathematics 2017-12-18 Roman Drnovšek , Aljoša Peperko

In this paper we give several expressions of spectral radius of a bounded operator on a Hilbert space, in terms of iterates of Aluthge transformation, numerical radius and the asymptotic behavior of the powers of this operator. Also we…

Functional Analysis · Mathematics 2016-06-21 Fadil Chabbabi , Mostafa Mbekhta

We describe all isometries of the $q$-numerical radius on the space ${\mathcal K}(\mathcal H)$ of compact operators on a (possibly infinite-dimensional) Hilbert space $\mathcal H$.

Functional Analysis · Mathematics 2021-02-18 Maria Inez Cardoso Gonçalves , Vladimir G. Pestov

We study the concepts of Birkhoff--James orthogonality and parallelism in Hilbert space operators, induced by the operator radius norm $w_{\rho}(\cdot)$. In particular, we completely characterize Birkhoff--James orthogonality and…

Functional Analysis · Mathematics 2024-05-14 Fuad Kittaneh , Ali Zamani

In this paper, we give some refinements for the second inequality in $\frac{1}{2}\|A\| \leq w(A) \leq \|A\|$, where $A\in B(H)$. In particular, if $A$ is hyponormal by refining the Young inequality with the Kantorovich constant $K(\cdot,…

Functional Analysis · Mathematics 2020-10-13 Zahra Heydarbeygi , Maryam Amyari , Mahnaz Khanehgir

Let $A$ be a positive operator on a Hilbert space $\mathcal{H}$ with $0<m\leq A\leq M$ and $X$ and $Y$ are two isometries on $\mathcal{H}$ such that $X^{*}Y=0$. For every 2-positive linear map $\Phi$, define…

Functional Analysis · Mathematics 2015-06-03 Pingping Zhang