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We prove the decomposition of arbitrary diagonal operators into tensor and matrix products of smaller matrices, focusing on the analytic structure of the resulting formulas and their inherent symmetries. Diagrammatic representations are…

Quantum Physics · Physics 2025-10-15 M. M. Fedin , A. A. Morozov

We give an alternative lower bound for the numerical radii of Hilbert space operators. As a by-product, we find conditions such that \begin{equation*} \omega\left(\left[\begin{array}{cc} 0 & R \\ S & 0 \end{array}\right]\right)=\frac{\Vert…

Functional Analysis · Mathematics 2019-03-28 M. Shah Hosseini , B. Moosavi , H. R. Moradi

We develop several upper and lower bounds for the $A$-Euclidean operator radius of $2$-tuple operators admitting $A$-adjoint, and show that they refine the earlier related bounds. As an application of the bounds developed here, we obtain…

Functional Analysis · Mathematics 2024-08-14 Suvendu Jana , Pintu Bhunia , Kallol Paul

The research on spectral inequalities for discrete Schrodinger Operators has proved fruitful in the last decade. Indeed, several authors analysed the operator's canonical relation to a tridiagonal Jacobi matrix operator. In this paper, we…

Functional Analysis · Mathematics 2013-12-09 Arman Sahovic

Consider $\mathcal{H}$ is a complex Hilbert space and $A$ is a positive operator on $\mathcal{H}.$ The mapping $\langle\cdot,\cdot\rangle_A: \mathcal{H}\times \mathcal{H} \to \mathbb {C}$, defined as $\left\langle…

Functional Analysis · Mathematics 2024-08-01 Messaoud Guesba , Somdatta Barik , Pintu Bhunia , Kallol Paul

Let $r_A(T)$ denote the $A$-spectral radius of an operator $T$ which is bounded with respect to the seminorm induced by a positive operator $A$ on a complex Hilbert space $\mathcal{H}$. In this paper, we aim to establish some $A$-spectral…

Functional Analysis · Mathematics 2020-02-10 Kais Feki

This note aims to present novel positive linear operators involving the Wright function. Furthermore, the present research established the moments of these newly defined operators and estimated the convergence rate using the classical…

Functional Analysis · Mathematics 2025-10-07 Prashantkumar Patel

We study different operator radii of homomorphisms from an operator algebra into $B(H)$ and show that these can be computed explicitly in terms of the usual norm. As an application, we show that if $\Omega$ is a $K$-spectral set for a…

Functional Analysis · Mathematics 2019-03-06 Catalin Badea , Michel Crouzeix , Hubert Klaja

In this study, the classical results on the joint numerical radius for $n$-tuples of Hilbert space operators are extended to the setting of the joint $(f,\delta)$-numerical radius. New and diverse contributions to this area are provided,…

Functional Analysis · Mathematics 2026-03-20 Zameddin I. Ismailov , Sergei Silvestrov , Pembe Ipek Al

To address the peculiarities of directed and/or signed graphs, new Laplacian operators have emerged. For instance, in the case of directionality, we encounter the magnetic operator, dilation (which is underexplored), operators based on…

Social and Information Networks · Computer Science 2024-06-04 Bruno Messias Farias de Resende

Let $\mu_\alpha$ be the Lebesgue plane measure on the unit disk with the radial weight $\frac{\alpha+1}{\pi}(1-|z|^2)^\alpha$. Denote by $\mathcal{A}^{2}_{n}$ the space of the $n$-analytic functions on the unit disk, square-integrable with…

Functional Analysis · Mathematics 2021-09-20 Roberto Moisés Barrera-Castelán , Egor A. Maximenko , Gerardo Ramos-Vazquez

The main object of this paper is to construct a new genuine Bernstein-Durrmeyer type operators which have better features than the classical one. Some direct estimates for the modified genuine Bernstein-Durrmeyer operator by means of the…

Numerical Analysis · Mathematics 2018-10-17 Ana Maria Acu , P. N. Agrawal

Let $A$ be a positive bounded operator on a Hilbert space $\big(\mathcal{H}, \langle \cdot, \cdot\rangle \big)$. The semi-inner product ${\langle x, y\rangle}_A := \langle Ax, y\rangle$, $x, y\in\mathcal{H},$ induces a seminorm…

Functional Analysis · Mathematics 2020-04-01 Ali Zamani

Optimal matrices for problems involving the matrix numerical radius often have fields of values that are disks, a phenomenon associated with partial smoothness. Such matrices are highly structured: we experiment in particular with the…

Optimization and Control · Mathematics 2020-05-01 X. Y. Han , Adrian S. Lewis

The main object of this paper is to construct new Durrmeyer type operators which have better features than the classical one. Some results concerning the rate of convergence and asymptotic formulas of the new operator are given. Finally,…

Numerical Analysis · Mathematics 2018-10-17 Ana Maria Acu , Vijay Gupta , Gancho Tachev

The main purpose of this note is to illustrate how the radius in a finite-dimensional power-associative algebra over a field $\mathbb{F}$, either $\mathbb{R}$ or $\mathbb{C}$, may change when the multiplication in this algebra is modified.…

Rings and Algebras · Mathematics 2015-11-10 Moshe Goldberg

The paper considers bounded linear radial operators on the polyanalytic Fock spaces $\mathcal{F}_n$ and on the true-polyanalytic Fock spaces $\mathcal{F}_{(n)}$. The orthonormal basis of normalized complex Hermite polynomials plays a…

Operator Algebras · Mathematics 2020-09-25 Egor A. Maximenko , Ana María Tellería-Romero

New upper and lower bounds for the numerical radii of Hilbert space operators are given. Among our results, we prove that if $A\in \mathcal{B} \left( \mathcal{H}\right) $ is a hyponormal operator, then for all non-negative non-decreasing…

Functional Analysis · Mathematics 2018-01-11 H. R. Moradi , M. E. Omidvar , K. Shebrawi

Solutions to optimization problems involving the numerical radius often belong to a special class: the set of matrices having field of values a disk centered at the origin. After illustrating this phenomenon with some examples, we…

Numerical Analysis · Mathematics 2024-12-20 Adrian S. Lewis , Michael L. Overton

In this study, some estimates are given for the $ (A,q)$-numerical radius and $ (A,q)$-Crawford number via the $ A$-numerical radius and $ A$-Crawford number for the $ A $-bounded linear operators in any complex semi-Hilbert space,…

Functional Analysis · Mathematics 2025-05-23 Pembe Ipek Al , Zameddin I. Ismailov , Fuad Kittaneh , Satyajit Sahoo