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The Euclidean operator radius of two bounded linear operators in the Hilbert $C^*$-module over $\A$ is given some precise bounds. Their relationship to recent findings in the literature that offer precise upper and lower bounds on the…

Functional Analysis · Mathematics 2023-07-06 M. H. M. Rashid

A generalization of the H\"older inequality is considered. Its relations with a previously obtained improvement of the Cauchy--Schwarz inequality are discussed.

Classical Analysis and ODEs · Mathematics 2017-01-17 Iosif Pinelis

In this paper, we will prove the sharp bounds of various operators in mixed radial angular spaces on Heisenberg groups. It mainly includes the boundedness of linear transformation eigenvalue operator in mixed radial angular space; Sharp…

Classical Analysis and ODEs · Mathematics 2023-07-06 Xiang Li , Huan Liang , Shaozhuang Xu , Dunyan Yan

In this paper, we introduce a new semi-norm of operators on a semi-Hilbertian space, which generalizes the A-numerical radius and A-operator semi-norm. We study the basic properties of this semi-norm, including upper and lower bounds for…

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

Let $A$ be a bounded linear positive operator on a complex Hilbert space $\mathcal{H}.$ Further, let $\mathcal{B}_A\mathcal{(H)}$ denote the set of all bounded linear operators on $\mathcal{H}$ whose $A$-adjoint exists, and $\mathbb{A}$…

Functional Analysis · Mathematics 2025-08-04 Nirmal Chandra Rout , Debasisha Mishra

We develop various lower bounds for the numerical radius $w(A)$ of a bounded linear operator $A$ defined on a complex Hilbert space, which improve the existing inequality $w^2(A)\geq \frac{1}{4}\|A^*A+AA^*\|$. In particular, for $r\geq 1$,…

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

We present several operator extensions of the Chebyshev inequality for Hilbert space operators. The main version deals with the synchronous Hadamard property for Hilbert space operators. Among other inequalities, it is shown that if…

Functional Analysis · Mathematics 2018-06-18 Mojtaba Bakherad , Silvestru Sever Dragomir

We obtain weighted mixed inequalities for operators associated to a critical radius function. We consider Schr\"odinger Calder\'on-Zygmund operators of $(s,\delta)$ type, for $1<s\leq \infty$ and $0<\delta \leq 1$. We also give estimates of…

Analysis of PDEs · Mathematics 2022-08-10 Fabio Berra , Gladis Pradolini , Pablo Quijano

We obtain several upper and lower bounds for the numerical radius of sectorial matrices. We also develop several numerical radius inequalities of the sum, product and commutator of sectorial matrices. The inequalities obtained here are…

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

Let $A$ be a non-zero positive bounded linear operator on a complex Hilbert space $(\mathcal{H},\langle\cdot,\cdot\rangle)$. Let $\omega_A(T)$ denote the $A$-numerical radius of an operator $T$ acting on the semi-Hilbert space…

Functional Analysis · Mathematics 2024-08-14 Pintu Bhunia , Kais Feki , Kallol Paul

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…

Functional Analysis · Mathematics 2024-02-08 B. Lins , A. Peperko

This paper explores refinements of some operator norm inequalities through the generalized spherical Aluthge transform and the spherical Heinz transform. We introduce the spherical Schatten $p$-norm for operator tuples and establish several…

Functional Analysis · Mathematics 2025-04-01 Fuad Kittaneh , Satyajit Sahoo , Hranislav Stanković

In this note, we present a refinement of the well-known AM-GM inequality. We use this improved inequalty to establish corresponding inequalities on Hilbert space. We also give some refinements of the Kantorovich inequality.

Functional Analysis · Mathematics 2021-11-08 Mehdi Eghbali Amlashi , Mahmoud Hassani

In this article we prove new inequalities for the generalized and the joint spectral radius of bounded sets of positive operators on Banach function and sequence spaces, in particular some inequalities for positive kernel operators that…

Functional Analysis · Mathematics 2023-11-07 Katarina Bogdanović

This paper introduces and investigates the concept of the $q$-numerical range for tuples of bounded linear operators in Hilbert spaces. We establish various inequalities concerning the $q$-numerical radius associated with these operator…

Functional Analysis · Mathematics 2024-10-08 Kais Feki , Arnab Patra , Jyoti Rani , Zakaria Taki

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

In this paper, we study the Bohr phenomenon for differential operators $D$ and $\mathscr{D}$ of stable harmonic mappings involving multiple Schwarz functions in $\mathcal{B}_n$, using distance formulations. By constructing suitable…

Complex Variables · Mathematics 2025-11-17 Sujoy Majumder , Nabadwip Sarkar , Molla Basir Ahamed

This paper is a sequel to [6]. In that paper we transferred the discussions in [1] and [13] concerning almost invariant half-spaces for operators on complex Banach spaces to the context of operators on Hilbert space, and we gave easier…

Functional Analysis · Mathematics 2017-10-30 Il Bong Jung , Eungil Ko , Carl Pearcy

Some special Hilbert spaces are introduced to present the class of infinitesimal operators with complete minimal non-basis family of eigenvectors. The discrete Hardy inequality plays an important role in the proposed approach. The…

Spectral Theory · Mathematics 2016-08-25 Grigory M. Sklyar , Vitalii Marchenko

In this note, some refinements of Young inequality and its reverse for positive numbers are proved and using these inequalities some operator versions and Hilbert-Schmidt norm versions for matrices of these inequalities are obtained.

Functional Analysis · Mathematics 2016-05-10 Alemeh Sheikhhosseini , Maryam Khosravi