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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…

Functional Analysis · Mathematics 2025-07-01 Pintu Bhunia , Messaoud Guesba

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

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

To extend the Euclidean operator radius, we define $w_p$ for an $n$-tuples of operators $(T_1,\ldots, T_n)$ in $\mathbb{B}(\mathscr{H})$ by $w_p(T_1,\ldots,T_n):= \sup_{\| x \| =1} \left(\sum_{i=1}^{n}| \langle T_i x, x \rangle |^p…

Functional Analysis · Mathematics 2015-02-03 M. S. Moslehian , M. Sattari , K. Shebrawi

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

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

This study presents new upper bounds for the numerical radii of operator matrices, with a focus on $n \times n$ and $2 \times 2$ block matrices acting on Hilbert space direct sums. By employing techniques such as the H\"older-McCarthy…

Functional Analysis · Mathematics 2025-08-05 M. H. M. Rashid

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

We develop a number of inequalities to obtain bounds for the numerical radius of a bounded linear operator defined on a complex Hilbert space using the properties of $t$-Aluthge transform. We show that the bounds obtained are sharper than…

Functional Analysis · Mathematics 2024-08-13 Santanu bag , Pintu Bhunia , Kallol Paul

In this paper, more inequalities between the operator norm and its numerical radius, for the class of normal operators, are established. Some of the obtained results are based on recent reverse results for the Schwarz inequality in Hilbert…

Functional Analysis · Mathematics 2012-10-29 Sever Silvestru Dragomir

The weighted numerical radius of a Hilbert space operator has been defined recently. This article explores other properties and uses this newly defined numerical radius to obtain several new interesting inequalities for the weighted…

Functional Analysis · Mathematics 2022-04-19 Cristian Conde , Mohammad Sababheh , Hamid Reza Moradi

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

Let ${\mathbb B}(\mathscr H)$ denote the set of all bounded linear operators on a complex Hilbert space ${\mathscr H}$. In this paper, we present some norm inequalities for sums of operators which are a generalization of some recent…

Functional Analysis · Mathematics 2023-10-10 Davood Afraza , Ramatollah Lashkaripoura , Mojtaba Bakherad

In this paper, we achieve new and improved numerical radius inequalities of operators defined on a Hilbert space by using Orlicz function and Hermite-Hadamard inequality. The upper bounds of various inequalities involving numerical radii…

Functional Analysis · Mathematics 2024-04-08 Amit Maji , Atanu Manna , Ram Mohapatra

Suppose $A=[a_{ij}]\in \mathcal{M}_n(\mathbb{C})$ is a complex $n \times n$ matrix and $B\in \mathcal{B}(\mathcal{H})$ is a bounded linear operator on a complex Hilbert space $\mathcal{H}$. We show that $w(A\otimes B)\leq w(C),$ where…

Functional Analysis · Mathematics 2026-01-16 Pintu Bhunia , Sujit Sakharam Damase , Apoorva Khare

We completely characterize the Crawford number attainment set and the numerical radius attainment set of a bounded linear operator on a Hilbert space. We study the intersection properties of the corresponding attainment sets of numerical…

Functional Analysis · Mathematics 2020-01-28 Debmalya Sain , Arpita Mal , Pintu Bhunia , Kallol Paul

Operator matrices have played a significant role in studying Hilbert space operators. In this paper, we discuss further properties of operator matrices and present new estimates for the operator norms and numerical radii of such operators.…

Functional Analysis · Mathematics 2022-06-28 Fuad Kittaneh , Hamid Reza Moradi , Mohammad Sababheh

New inequalities for the $A$-numerical radius of the products and sums of operators acting on a semi-Hilbert space, i.e. a space generated by a positive semidefinite operator $A$, are established. In particular, it is proved for operators…

Functional Analysis · Mathematics 2020-12-23 Pintu Bhunia , Kais Feki , Kallol Paul

In this work, a pre-Gr\"{u}ss inequality for positive Hilbert space operators is proved. So that, some numerical radius inequalities are proved. On the other hand, based on a non-commutative Binomial formula, a non-commutative upper bound…

Functional Analysis · Mathematics 2018-11-21 Mohammad W. Alomari

In this work, some generalizations and refinements inequalities for numerical radius of the product of Hilbert space operators are proved. New inequalities for numerical radius of block matrices of Hilbert space operators are also…

Functional Analysis · Mathematics 2019-03-18 Mohammad W. Alomari