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In this paper we introduce and prove some properties of $(\alpha;\beta)$-normal operators according to semi-Hilbertian space structures. Furthermore we s,ate various inequalities between the A-operator norm and A-numerical radius of…

Functional Analysis · Mathematics 2016-10-12 Abdelkader Benali , Ould Ahmed Mahmoud Sid Ahmed

Starting from a general operator representation in the time-frequency domain, this paper addresses the problem of approximating linear operators by operators that are diagonal or band-diagonal with respect to Gabor frames. A…

Analysis of PDEs · Mathematics 2008-09-17 Monika Dorfler , Bruno Torresani

In this paper, we give upper and lower bounds for the spectral radius of a nonnegative irreducible matrix and characterize the equality cases. These bounds theoretically improve and generalize some known results of Duan et al.[X. Duan, B.…

Combinatorics · Mathematics 2013-10-22 Shu-Yu Cui , Gui-Xian Tian

We consider Cahn-Hilliard equations with external forcing terms. Energy decreasing and mass conservation might not hold. We show that level surfaces of the solutions of such generalized Cahn-Hilliard equations tend to the solutions of a…

Analysis of PDEs · Mathematics 2013-01-08 D. C. Antonopoulou , G. D. Karali , E. Orlandi

In this paper, we will use the conclusions and methods in \cite{1} to obtain the sharp bounds for a class of integral operators with the nonnegative kernels in weighted-type spaces on Heisenberg group. As promotions, the sharp bounds of…

Classical Analysis and ODEs · Mathematics 2023-04-19 Xiang Li , Zhanpeng Gu , Dunyan Yan , Zhongci Hang

We give an alternative proof of recent results by the authors on uniform boundedness of dyadic averaging operators in (quasi-)Banach spaces of Hardy-Sobolev and Triebel-Lizorkin type. This result served as the main tool to establish…

Functional Analysis · Mathematics 2017-03-01 Gustavo Garrigós , Andreas Seeger , Tino Ullrich

We consider the elliptical range theorems for the Davis--Wielandt shell, the numerical range, and the conformal range in terms of and related to their quadratic representations. The emphasis is on exposing a variety of elementary…

Spectral Theory · Mathematics 2026-03-10 Gyula Lakos

In this paper the complete solution of the restricted inequalities for supremal operators are given. The boundedness of the composition of supremal operators with the Hardy and Copson operators in weighted Lebesgue spaces are characterized.

Functional Analysis · Mathematics 2020-02-05 Amiran Gogatishvili , Rza Mustafayev

In this paper, we obtain the sharp upper and lower bounds for the spectral radius of a nonnegative weakly irreducible tensor. We also apply these bounds to the adjacency spectral radius and signless Laplacian spectral radius of a uniform…

Combinatorics · Mathematics 2018-07-31 Lihua You , Xiaohua Huang , Xiying Yuan

By the help of power series f we can naturally construct another power series that has as coefficients the absolute values of the coefficients of f. Utilising these functions we prove some inequalities for the spectral radius of the bounded…

Functional Analysis · Mathematics 2013-02-13 S. S. Dragomir

We give sharp upper bounds for the ordinary spectral radius and signless Laplacian spectral radius of a uniform hypergraph in terms of the average $2$-degrees or degrees of vertices, respectively, and we also give a lower bound for the…

Combinatorics · Mathematics 2016-05-20 Hongying Lin , Biao Mo , Bo Zhou , Weiming Weng

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

Let $H$ be a real Hilbert space. In this short note, using some of the properties of bounded linear operators with closed range defined on $H$, certain bounds for a specific convex subset of the solution set of infinite linear…

Functional Analysis · Mathematics 2020-06-30 Projesh Nath Choudhury , M. Rajesh Kannan , K. C. Sivakumar

In this paper, we introduce and study frame of operators in quaternionic Hilbert spaces as a generalization of g frames which in turn generalized various notions like Pseduo frames, bounded quasi-projectors and frame of subspaces (fusion…

Functional Analysis · Mathematics 2020-03-03 S. K. Sharma , A. M. Jarrah , S. K. Kaushik

A new functional calculus, developed recently for a fully non-perturbative treatment of quantum gravity, is used to begin a systematic construction of a quantum theory of geometry. Regulated operators corresponding to areas of 2-surfaces…

General Relativity and Quantum Cosmology · Physics 2010-04-06 Abhay Ashtekar , Jerzy Lewandowski

In this paper, we aim to establish a range of numerical radius inequalities. These discoveries will bring us to a recently validated numerical radius inequality and will present numerical radius inequalities that exhibit enhanced precision…

Functional Analysis · Mathematics 2024-10-07 M. H. M. Rashid

In this paper, we introduce a new type of parallelism for bounded linear operators on a Hilbert space $\big(\mathscr{H}, \langle \cdot ,\cdot \rangle\big)$ based on numerical radius. More precisely, we consider operators $T$ and $S$ which…

Functional Analysis · Mathematics 2018-10-25 Marzieh Mehrazin , Maryam Amyari , Ali Zamani

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

The concept of the Bohr radius of a pair of operators is introduced. In terms of the convolution function, a general formula for calculating the Bohr radius of the Hadamard convolution type operator with a fixed initial coefficient is…

Complex Variables · Mathematics 2023-10-05 Ramis Khasyanov

We describe here the higher rank numerical range, as defined by Choi, Kribs and Zyczkowski, of a normal operator on an infinite dimensional Hilbert space in terms of its spectral measure. This generalizes a result of Avendano for…

Functional Analysis · Mathematics 2023-02-09 Pankaj Dey , Mithun Mukherjee
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