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We prove new inequalities for the essential generalized and the essential joint spectral radius of Hadamard (Schur) weighted geometric means of bounded sets of infinite nonnegative matrices that define operators on suitable Banach sequence…

泛函分析 · 数学 2024-02-08 B. Lins , A. Peperko

In this paper, we improve the famous Reid Inequality related to linear operators. Some monotony results for positive operators are also established with a different approach from what is known in the existing literature. Lastly, Reid and…

泛函分析 · 数学 2017-07-12 Souheyb Dehimi , Mohammed Hichem Mortad

Motivated by the refinements and reverses of arithmetic-geometric mean and arithmetic-harmonic mean inequalities for scalars and matrices, in this article, we generalize the scalar and matrix inequalities for the difference between…

泛函分析 · 数学 2015-01-21 Wenshi Liao , Junliang Wu

In this paper, we derive a generalized multiplicative Hardy-Littlewood-Polya type inequality, as well as several related additive inequalities, for functions of operators in Hilbert spaces. In addition, we find the modulus of continuity of…

泛函分析 · 数学 2015-10-06 Vladyslav Babenko , Yuliya Babenko , Nadiia Kriachko

In this paper, we introduce the concept of operator arithmetic-geometrically convex functions for positive linear operators and prove some Hermite-Hadamard type inequalities for these functions. As applications, we obtain trace inequalities…

泛函分析 · 数学 2016-03-16 Ali Taghavi , Vahid Darvish , Haji Mohammad Nazari

Different estimates for the norm of the self-commutator of a Hilbert space operator are proposed. Particularly, this norm is bounded from above by twice of the area of the numerical range of the operator. An isoperimetric-type inequality is…

谱理论 · 数学 2014-05-08 Gevorgyan Levon

In this paper we introduce operator s-convex func- tions and establish some Hermite-Hadamard type inequalities in which some operator s-convex functions of positive operators in Hilbert spaces are involved.

泛函分析 · 数学 2014-07-10 Amir Ghasem Ghazanfari

We propose a new viewpoint on Hilbert scales extending them by means of all Hilbert spaces that are interpolation ones between spaces on the scale. We prove that this extension admits an explicit description with the help of…

泛函分析 · 数学 2021-02-17 Vladimir Mikhailets , Aleksandr Murach , Tetiana Zinchenko

We obtain several sharp lower and upper bounds for the Euclidean operator radius of a pair of bounded linear operators defined on a complex Hilbert space. As applications of these bounds we deduce a chain of new bounds for the classical…

泛函分析 · 数学 2024-08-14 Suvendu Jana , Pintu Bhunia , Kallol Paul

Let $\mathcal{B}(\mathcal{H})$ be the algebra of all bounded linear operators on a complex Hilbert space $\mathcal{H}$. In this paper, we first establish several sharp improved and refined versions of the Bohr's inequality for the functions…

泛函分析 · 数学 2026-04-15 Vasudevarao Allu , Himadri Halder

We study the spectral properties of bounded and unbounded Jacobi matrices whose entries are bounded operators on a complex Hilbert space. In particular, we formulate conditions assuring that the spectrum of the studied operators is…

谱理论 · 数学 2019-02-08 Grzegorz Świderski

Some sharp discrete inequalities in normed linear spaces are obtained. New reverses of the generalised triangle inequality are also given.

泛函分析 · 数学 2007-05-23 Sever Silvestru Dragomir

We obtain upper and lower bounds for the Davis-Wielandt radius of bounded linear operators defined on a complex Hilbert space, which improve on the existing ones. We also obtain bounds for the Davis-Wielandt radius of operator matrices. We…

泛函分析 · 数学 2024-08-14 Pintu Bhunia , Aniket Bhanja , Santanu Bag , Kallol Paul

This paper investigates new properties of $q$-numerical ranges for compact normal operators and establishes refined upper bounds for the $q$-numerical radius of Hilbert space operators. We first prove that for a compact normal operator $T$…

泛函分析 · 数学 2025-12-17 Mohammad H. M. Rashid

Let $A=[A_{ij}]$ be an $n\times n$ operator matrix where each $A_{ij}$ is a bounded linear operator on a complex Hilbert space $\mathcal{H}$. With other numerical radius bounds via contraction operators, we show that $w(A) \leq…

泛函分析 · 数学 2024-07-10 Pintu Bhunia

Given a Hilbert module $H$ over a $C^*$-algebra, let $\mathcal{L}(H)$ be the set of all adjointable operators on $H$. For each $T\in\mathcal{L}(H)$, its numerical radius is defined by $w(T)=\sup\big\{\|\langle Tx, x \rangle\|: x\in H,…

泛函分析 · 数学 2025-02-28 J. Li , K. Wu , Q. Xu

We introduce a new seminorm of $n$-tuple operators, which generalizes the $A$-Euclidean operator radius of $n$-tuple bounded linear operators on a complex Hilbert space. We introduce and study basic properties of this seminorm. As an…

泛函分析 · 数学 2025-07-01 Pintu Bhunia , Messaoud Guesba

For a bounded linear operator $T$ acting on a reproducing kernel Hilbert space $\mathcal{H}(\Omega)$ over some non-empty set $\Omega$, the Berezin range and the Berezin radius of $T$ are defined respectively, by $\text{Ber}(T) := \{\langle…

泛函分析 · 数学 2024-11-19 Athul Augustine , M. Garayev , P. Shankar

In this paper, we improve and generalize the operator versions of Kantorovich and Wielandt inequalities for positive linear maps on Hilbert space. Our results are more extensive and precise than many previous results due to Fu and He…

泛函分析 · 数学 2015-01-14 Wenshi Liao , Junliang Wu

We introduce compactness classes of Hilbert space operators by grouping together all operators for which the associated singular values decay at a certain speed and establish upper bounds for the norm of the resolvent of operators belonging…

谱理论 · 数学 2020-05-29 Ayse Guven , Oscar F. Bandtlow