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We develop several Euclidean operator radius bounds for the product of two $d$-tuple operators using positivity criteria of a $2\times 2$ block matrix whose entries are $d$-tuple operators. From these bounds, by using the polar…

Functional Analysis · Mathematics 2023-08-21 Pintu Bhunia , Suvendu Jana , Kallol Paul

Several refinements of norm and numerical radius inequalities of bounded linear operators on a complex Hilbert space are given. In particular, we show that if $A$ is a bounded linear operator on a complex Hilbert space, then $$…

Functional Analysis · Mathematics 2024-08-23 Pintu Bhunia , Kallol Paul

Suppose $\mathcal{H}_1, \mathcal{H}_2, \ldots, \mathcal{H}_n$ are arbitrary complex Hilbert spaces, and ${\bf A}=[A_{ij}]$ is an $n\times n$ operator matrix with $A_{ij}\in \mathcal{B}(\mathcal{H}_j, \mathcal{H}_i).$ We show that $w({\bf…

Functional Analysis · Mathematics 2025-03-05 Pintu Bhunia

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

In this paper, the $q$-numerical radius of operators in semi-Hilbertian spaces is studied. New characterizations are established, and sharp upper and lower bounds for the $q$-numerical radius are derived. Moreover, several inequalities…

Functional Analysis · Mathematics 2026-03-19 Jyoti Rani

In this article, we employ a standard convex argument to obtain new and refined inequalities related to the matrix mean of two accretive matrices, the numerical radius and the Tsallis relative operator entropy.

Functional Analysis · Mathematics 2021-04-28 Hamid Reza Moradi , Shigeru Furuichi , Mohammad Sababheh

In this article, we prove an inner product inequality for Hilbert space operators. This inequality, then, is utilized to present a general numerical radius inequality using convex functions. Applications of the new results include obtaining…

Functional Analysis · Mathematics 2022-07-19 Zahra Heydarbeygi , Mohammad Sababheh , Hamid Reza Moradi

This article improves the triangle inequality for complex numbers, using the Hermite-Hadamard inequality for convex functions. Then, applications of the obtained refinement are presented to include some operator inequalities. The operator…

Functional Analysis · Mathematics 2022-04-19 Shigeru Furuichi , Mohammad Sababheh , Hamid Reza Moradi

The main purpose of this paper is, in the general setting of the adjointable operators on Hilbert $C^*$-modules, to develop two new tools that can be applied to deal with the positive solutions of certain operator equations, the operator…

Functional Analysis · Mathematics 2024-06-14 Mohammad Sababheh , Hamid Reza Moradi , Qingxiang Xu , Shuo Zhao

In this article, we explore the celebrated Gr\"{u}ss inequality, where we present a new approach using the Gr\"{u}ss inequality to obtain new refinements of operator means inequalities. We also present several operator Gr\"{u}ss-type…

Functional Analysis · Mathematics 2020-09-17 H. R. Moradi , S. Furuichi , Z. Heydarbeygi , M. Sababheh

The paper considers some new properties of the so-called $A$-maximal numerical range of operators, denoted by $W_{\max}^A(\cdot)$, where $A$ is a positive bounded linear operator acting on a complex Hilbert space $\mathcal{H}$. Some…

Functional Analysis · Mathematics 2023-02-02 Abderrahim Baghdad , El Hassan Benabdi , Kais Feki

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

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

The main goal of this paper is to discuss the recent advancements of operator means for accretive matrices in a more general setting. In particular, we present the general form governing the well established definition of geometric mean,…

Functional Analysis · Mathematics 2021-04-16 Yassine Bedrani , Fuad Kittaneh , Mohammed Sababheh

Let $A$ be a positive bounded linear operator on a complex Hilbert space $\mathcal{H}$ and $\mathcal{B}_{A}(\mathcal{H})$ be the subspace of all operators which admit $A$-adjoints operators. In this paper, we establish some inequalities…

Functional Analysis · Mathematics 2021-09-21 Kais Feki

We prove numerical radius inequalities involving commutators of $G_{1}$ operators and certain analytic functions. Among other inequalities, it is shown that if $A$ and $X$ are bounded linear operators on a complex Hilbert space, then…

Functional Analysis · Mathematics 2017-09-07 Mojtaba Bakherad , Fuad Kittaneh

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

Let $\mathcal{A}$ be a unital $\mathbf{C}^*$-algebra with unit $e$. We develop several inequalities for a positive linear functional $f$ on $\mathcal{A}$ and obtain several bounds for the numerical radius $v(a)$ of an element $a\in…

Functional Analysis · Mathematics 2024-10-04 Pintu Bhunia

In this paper, we examine the problem of approximating a general linear dimensionality reduction (LDR) operator, represented as a matrix $A \in \mathbb{R}^{m \times n}$ with $m < n$, by a partial circulant matrix with rows related by…

Machine Learning · Statistics 2015-02-26 Swayambhoo Jain , Jarvis Haupt

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…

Functional Analysis · Mathematics 2024-08-14 Pintu Bhunia , Aniket Bhanja , Santanu Bag , Kallol Paul
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