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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.…

泛函分析 · 数学 2023-09-21 Mohammad Sababheh , Hamid Reza Moradi , Mohammad Alomari

This paper is a continuation of a recent work on a new norm, christened the $ (\alpha, \beta)$-norm, on the space of bounded linear operators on a Hilbert space. We obtain some upper bounds for the said norm of $n\times n$ operator…

泛函分析 · 数学 2024-08-14 P. Bhunia , A. Bhanja , D. Sain , K. Paul

We obtain upper bounds for the numerical radius of a product of Hilbert space operators which improve on the existing upper bounds. We generalize the numerical radius inequalities of $n\times n$ operator matrices by using non-negative…

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

This study utilizes Orlicz functions to provide refined lower and upper bounds on the q-numerical radius of an operator acting on a Hilbert space. Additionally, the concept of q-sectorial matrices is introduced and further bounds for the…

泛函分析 · 数学 2025-04-30 Fuad Kittaneh , Arnab Patra , Jyoti Rani

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

The main aim of this article is to establish several $p$-numerical radius inequalities via the $(f,g)$-Aluthge transform of Hilbert space operators and operator matrices. Furthermore, various classical numerical radius and norm inequalities…

泛函分析 · 数学 2025-04-08 Satyajit Sahoo

We develope new lower bounds for the $A$-numerical radius of semi-Hilbertian space operators, and applying these bounds we obtain upper bounds for the $A$-numerical radius of the commutators of operators. The bounds obtained here improve on…

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

This article introduces several new upper bounds for the $q$-numerical radius of bounded linear operators on complex Hilbert spaces. Our results refine some of the existing upper bounds in this field. The $q$-numerical radius inequalities…

泛函分析 · 数学 2023-06-08 Arnab Patra , Falguni Roy

Let $A$ be a positive operator on a complex Hilbert space $\mathcal{H}.$ We present inequalities concerning upper and lower bounds for $A$-numerical radius of operators, which improve on and generalize the existing ones, studied recently in…

泛函分析 · 数学 2024-08-13 Pintu Bhunia , Kallol Paul , Raj Kumar Nayak

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…

泛函分析 · 数学 2026-03-19 Jyoti Rani

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…

泛函分析 · 数学 2021-03-09 Shiva Sheybani , Mohammed Sababheh , Hamid Reza Moradi

We give an expression for a generalized numerical radius of Hilbert space operators and then apply it to obtain upper and lower bounds for the generalized numerical radius. We also establish some generalized numerical radius inequalities…

泛函分析 · 数学 2019-09-26 A. Zamani , M. S. Moslehian , Q. Xu , C. Fu

In this paper, we present several new bounds for the norm and numerical radius of sums of Hilbert space operators. The obtained bounds form a new collection that enriches our understanding of these bounds. We compare our bounds with the…

泛函分析 · 数学 2026-02-17 Zameddin I. Ismailov , Pembe Ipek Al , Hamid Reza Moradi , Mohammad Sababheh

Let $\mathcal{H}$ be a complex Hilbert space and let $A$ be a positive operator on $\mathcal{H}$. We obtain new bounds for the $A$-numerical radius of operators in semi-Hilbertian space $\mathcal{B}_A(\mathcal{H})$ that generalize and…

泛函分析 · 数学 2024-08-14 Pintu Bhunia , Raj Kumar Nayak , Kallol Paul

We establish new integral inequalities for the numerical radius and the operator norm of bounded linear operators on Hilbert spaces. Our results refine classical triangle-type and operator matrix inequalities by incorporating convex…

泛函分析 · 数学 2026-02-17 Shiva Sheybani , Hamid Reza Moradi , Mohammad Sababheh

We completely characterize Birkhoff-James orthogonality with respect to numerical radius norm in the space of bounded linear operators on a complex Hilbert space. As applications of the results obtained, we estimate lower bounds of…

泛函分析 · 数学 2024-08-13 Arpita Mal , Kallol Paul , Jeet Sen

We give an alternative lower bound for the numerical radii of Hilbert space operators. As a by-product, we find conditions such that \begin{equation*} \omega\left(\left[\begin{array}{cc} 0 & R \\ S & 0 \end{array}\right]\right)=\frac{\Vert…

泛函分析 · 数学 2019-03-28 M. Shah Hosseini , B. Moosavi , H. R. Moradi

In this article, we developed a series of new inequalities involving the $q$-numerical radius for operators and $2\times 2$ operator matrices. These inequalities serve to establish both lower and upper bounds for the $q$-numerical radius of…

泛函分析 · 数学 2025-02-07 Satyajit Sahoo , Nirmal Chandra Rout

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

We introduce a new norm on the space of bounded linear operators on a complex Hilbert space, which generalizes the numerical radius norm, the usual operator norm and the modified Davis-Wielandt radius. We study basic properties of this…

泛函分析 · 数学 2024-08-14 D. Sain , P. Bhunia , A. Bhanja , K. Paul
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