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Let $\mathbf{T}=(T_1,\ldots,T_d)$ be a $d$-tuple of operators on a complex Hilbert space $\mathcal{H}$. The spherical Aluthge transform of $\mathbf{T}$ is the $d$-tuple given by…

泛函分析 · 数学 2020-04-07 Kais Feki , Takeaki Yamazaki

In this paper, we show some refinements of generalized numerical radius inequalities involving the Young and Heinz inequalities. In particular, we present \begin{align*}…

泛函分析 · 数学 2018-05-22 Monire Hajmohamadi , Rahmatollah Lashkaripour , Mojtaba Bakherad

Let $A = U |A|$ be the polar decomposition of $A$. The Aluthge transform of the operator $A$, denoted by $\tilde{A}$, is defined as $\tilde{A} =|A|^{\frac{1}{2}} U |A|^{\frac{1}{2}}$. In this paper, first we generalize the definition of…

泛函分析 · 数学 2017-10-16 Mojtaba Bakherad , Khalid Shebrawi

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…

泛函分析 · 数学 2022-07-19 Zahra Heydarbeygi , Mohammad Sababheh , Hamid Reza Moradi

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…

泛函分析 · 数学 2024-08-14 Pintu Bhunia , Kais Feki , Kallol Paul

They proved several properties and introduced some inequalities. We continue with the study of this generalized numerical radius and we develop diverse inequalities involving w_N. We also study particular cases with a fixed N(.), for…

泛函分析 · 数学 2020-06-29 Tamara Bottazzi , Cristian Conde

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…

泛函分析 · 数学 2024-04-08 Amit Maji , Atanu Manna , Ram Mohapatra

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…

泛函分析 · 数学 2015-11-09 Mostafa Sattari , Mohammad Sal Moslehian , Takeaki Yamazaki

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…

泛函分析 · 数学 2022-04-19 Cristian Conde , Mohammad Sababheh , Hamid Reza Moradi

This paper establishes several new inequalities for the $A$-norm and $A$-numerical radius of operator sums in semi-Hilbertian spaces, significantly advancing the existing theory. We present two fundamental refinements of the generalized…

泛函分析 · 数学 2025-07-09 M. H. M. Rashid

Some new inequalities for the norm and the numerical radius of composite operators generated by a pair of operators are given.

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

Consider a complex Hilbert space $\left(\mathcal{H}, \langle \cdot, \cdot \rangle\right)$ equipped with a positive bounded linear operator $A$ on $\mathcal{H}$. This induces a semi-norm $\|\cdot\|_A$ through the semi-inner product $\langle…

泛函分析 · 数学 2025-07-09 M. H. M. Rashid

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…

泛函分析 · 数学 2025-08-05 M. H. M. Rashid

The main goal of this paper is to present new bounds for certain inner products in Hilbert spaces, with applications to the numerical radius and the operator norm. The obtained results significantly improve earlier results in this…

泛函分析 · 数学 2026-01-06 Mohammad Sababheh , Hamid Reza Moradi

In this paper, we introduce the $f-$operator radius of Hilbert space operators as a generalization of the Euclidean operator radius and the $q-$operator radius. Properties of the newly defined radius are discussed, emphasizing how it…

泛函分析 · 数学 2022-11-02 Mohammad W. Alomari , Mohammad Sababheh , Cristian Conde , Hamid Reza Moradi

This paper establishes new upper bounds for the $A$-numerical radius of operator matrices in semi-Hilbertian spaces by leveraging the $A$-Buzano inequality and developing refined techniques for operator matrices. We present several sharp…

泛函分析 · 数学 2025-07-08 M. H. M. Rashid

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…

泛函分析 · 数学 2024-08-13 Pintu Bhunia , Kais Feki , Kallol Paul

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

泛函分析 · 数学 2020-04-20 Kais Feki

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…

泛函分析 · 数学 2026-02-05 Shankhadeep Mondal , Ram Narayan Mohapatra , Kasun Tharuka Dewage

We present some upper and lower bounds for the numerical radius of a bounded linear operator defined on complex Hilbert space, which improves on the existing upper and lower bounds. We also present an upper bound for the spectral radius of…

泛函分析 · 数学 2024-08-13 Pintu Bhunia , Santanu Bag , Kallol Paul