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The two well-known numerical radius inequalities for the tensor product $A \otimes B$ acting on $\mathbb{H} \otimes \mathbb{K}$, where $A$ and $B$ are bounded linear operators defined on complex Hilbert spaces $\mathbb{H} $ and $…

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

In this article, we obtain several new weighted bounds for the numerical radius of a Hilbert space operator. The significance of the obtained results is the way they generalize many existing results in the literature; where certain values…

Functional Analysis · Mathematics 2021-03-09 Shiva Sheybani , Mohammed Sababheh , Hamid Reza Moradi

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

Relatively recently, K.M.R. Audenaert (2010), R.A. Horn and F. Zhang (2010), Z. Huang (2011), A.R. Schep (2011), A. Peperko (2012), D. Chen and Y. Zhang (2015) have proved inequalities on the spectral radius and the operator norm of…

Functional Analysis · Mathematics 2017-12-18 Roman Drnovšek , Aljoša Peperko

In this paper, we begin by showing a new generalization of the celebrated Cauchy-Schwarz inequality for the inner product. Then, this generalization is used to present some bounds for the Euclidean operator radius and the Euclidean operator…

Functional Analysis · Mathematics 2023-10-09 Mohammad Sababheh , Hamid Reza Moradi

In this paper, we develop several Euclidean operator radius inequalities of $d$-tuple operators, as well as the sum and the product of $d$-tuple operators. Also, we obtain a power inequality for the Euclidean operator radius. Further, we…

Functional Analysis · Mathematics 2023-04-18 Suvendu Jana , Pintu Bhunia , Kallol Paul

We generalize several inequalities involving powers of the numerical radius for product of two operators acting on a Hilbert space. For any $A, B, X\in \mathbb{B}(\mathscr{H})$ such that $A,B$ are positive, we establish some numerical…

Functional Analysis · Mathematics 2015-11-09 Mostafa Sattari , Mohammad Sal Moslehian , Takeaki Yamazaki

In this article, we present some new inequalities for numerical radius of Hilbert space operators via convex functions. Our results generalize and improve earlier results by El-Haddad and Kittaneh. Among several results, we show that if…

Functional Analysis · Mathematics 2019-07-16 S. Tafazoli , H. R. Moradi , S. Furuichi , P. Harikrishnan

We develop upper and lower bounds for the numerical radius of $2\times 2$ off-diagonal operator matrices, which generalize and improve on the existing ones. We also show that if $A$ is a bounded linear operator on a complex Hilbert space…

Functional Analysis · Mathematics 2021-10-07 Pintu Bhunia , Kallol Paul

In this paper, we aim to introduce and characterize the concept of numerical radius orthogonality of operators on a complex Hilbert space $\mathcal{H}$ which are bounded with respect to the semi-norm induced by a positive operator $A$ on…

Functional Analysis · Mathematics 2024-08-13 Pintu Bhunia , Kais Feki , Kallol Paul

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 work, some new upper and lower bounds of the Davis-Wielandt radius are introduced. Generalizations of some presented results are obtained. Some bounds of the Davis-Wielandt radius for $n\times n$ operator matrices are established.…

Functional Analysis · Mathematics 2020-08-04 Mohammad W. Alomari

Let $\mathbb{A}= \begin{pmatrix} A & 0 \\ 0 & A \\ \end{pmatrix} $ be a $2\times2$ diagonal operator matrix whose each diagonal entry is a bounded positive (semidefinite) linear operator $A$ acting on a complex Hilbert space $\mathcal{H}$.…

Functional Analysis · Mathematics 2022-04-04 Kais Feki , Satyajit Sahoo

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 paper, we investigate the generalized numerical radius $\omega_N$, associated with a matrix norm $N$ defined by $\omega_N(X) = \sup_{\theta \in \mathbb{R}} N(\operatorname{Re}(e^{i\theta}X))$. We focus on matrices whose numerical…

Functional Analysis · Mathematics 2025-06-04 Mohammad Alakhrass

We establish new upper bounds for the numerical radius of bounded linear operators on a complex Hilbert space by introducing weighted geometric means of the modulus of an operator and its adjoint. This approach yields a family of…

Functional Analysis · Mathematics 2026-02-05 Shankhadeep Mondal , Ram Narayan Mohapatra , Kasun Tharuka Dewage

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, we show several bounds for the numerical radius of a Hilbert space operator in terms of the Euclidean operator norm. The obtained forms will enable us to find interesting refinements of celebrated results in the literature.…

Functional Analysis · Mathematics 2023-09-21 Mohammad Sababheh , Hamid Reza Moradi , Mohammad Alomari

For a given bounded positive (semidefinite) linear operator $A$ on a complex Hilbert space $\big(\mathcal{H}, \langle \cdot\mid \cdot\rangle \big)$, we consider the semi-Hilbertian space $\big(\mathcal{H}, \langle \cdot\mid \cdot\rangle_A…

Functional Analysis · Mathematics 2020-05-13 Kais Feki

In this paper we prove a conjecture stated by the first two authors establishing the closure of the numerical range of a certain class of $n+1$-periodic tridiagonal operators as the convex hull of the numerical ranges of two tridiagonal…

Functional Analysis · Mathematics 2022-05-13 Benjamín A. Itzá-Ortiz , Rubén A. Martínez-Avendaño , Hiroshi Nakazato