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Let $\mathcal{B}(\mathcal{H})$ be the algebra of all bounded linear operators on a complex Hilbert space $\mathcal{H}$. In this paper, we first establish several sharp improved and refined versions of the Bohr's inequality for the functions…

Functional Analysis · Mathematics 2026-04-15 Vasudevarao Allu , Himadri Halder

We develop a new refinement of the Kato's inequality and using this refinement we obtain several upper bounds for the numerical radius of a bounded linear operator as well as the product of operators, which improve the well known existing…

Functional Analysis · Mathematics 2024-07-09 Pintu Bhunia , Satyajit Sahoo

We prove some refinements of an inequality due to X. Zhan in an arbitrary complex Hilbert space by using some results on the Heinz inequality. We present several related inequalities as well as new variants of the Corach--Porta--Recht…

Functional Analysis · Mathematics 2012-03-21 Cristian Conde , Mohammad Sal Moslehian , Ameur Seddik

Let $A=[A_{ij}]$ be an $n\times n$ operator matrix where each $A_{ij}$ is a bounded linear operator on a complex Hilbert space $\mathcal{H}$. With other numerical radius bounds via contraction operators, we show that $w(A) \leq…

Functional Analysis · Mathematics 2024-07-10 Pintu Bhunia

We present unified approach to obtain sharp mean-squared and multiplicative inequalities of Hardy-Littlewood-Poly\'a and Taikov types for multiple closed operators acting on Hilbert space. We apply our results to establish new sharp…

Functional Analysis · Mathematics 2022-01-19 Vladislav Babenko , Yuliya Babenko , Nadiia Kriachko , Dmytro Skorokhodov

In this paper, we study the relationship between operator space norm and operator space numerical radius on the matrix space $\mathcal{M}_n(X)$, when $X$ is a numerical radius operator space. Moreover, we establish several inequalities for…

Operator Algebras · Mathematics 2021-07-23 Mohammad Sal Moslehian , Mostafa Sattari

The main aim of this book is to present recent results concerning inequalities for continuous functions of selfadjoint operators on complex Hilbert spaces. It is intended for use by both researchers in various fields of Linear Operator…

Functional Analysis · Mathematics 2012-03-09 Silvestru Sever Dragomir

Let $A$ be a bounded linear operator on a complex Hilbert space and $\Re(A)$ ( $\Im(A)$ ) denote the real part (imaginary part) of A. Among other refinements of the lower bounds for the numerical radius of $A$, we prove that…

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

We present several sharp upper bounds and some extension for product operators. Among other inequalities, it is shown that if , , are non-negative continuous functions on such that , , then for all non-negative operator monotone decreasing…

Functional Analysis · Mathematics 2020-04-22 Hosna Jafarmanesh , Maryam Khosravi

The numerical radius of a matrix is a scalar quantity that has many applications in the study of matrix analysis. Due to the difficulty in computing the numerical radius, inequalities bounding it have received a considerable attention in…

Functional Analysis · Mathematics 2020-07-20 Yassine Bedrani , Fuad Kittaneh , Mohammed Sababheh

Let $A, B$ and $X$ be $n\times n$ matrices such that $A, B$ are positive semidefinite. We present some refinements of the matrix Cauchy-Schwarz inequality by using some integration techniques and various refinements of the Hermite--Hadamard…

Functional Analysis · Mathematics 2014-11-25 Mojtaba Bakherad

In this paper, we will study $n$-dimensional Hardy operator and its dual in mixed radial-angular spaces on Heisenberg groups and obtain their sharp bounds by using the rotation method. Furthermore, the sharp bounds of $n$-dimensional…

Classical Analysis and ODEs · Mathematics 2023-04-25 Zhongci Hang , Xiang Li , Dunyan Yan

In this article, we prove several multi-term refinements of Young type inequalities for both real numbers and operators improving several known results. Among other results, we prove \begin{eqnarray*}…

Functional Analysis · Mathematics 2016-10-11 Mohammad Sababheh , Mohammad Sal Moslehian

In this paper, we provide some inequalities for $P$-class functions and self-adjoint operators on a Hilbert space including an operator version of the Jensen's inequality and the Hermite-Hadamard's type inequality. We improve the…

Functional Analysis · Mathematics 2020-01-22 Ismail Nikoufar , Davuod Saeedi

We prove a sharpened version of the Strichartz inequality for radial solutions of the Schr\"odinger equation in $\mathbb{R}^2\times \mathbb{R}$. We establish an improved upper bound for functions that nearly extremize the inequality, with a…

Classical Analysis and ODEs · Mathematics 2018-07-26 Felipe Gonçalves

Motivated by the refinements and reverses of arithmetic-geometric mean and arithmetic-harmonic mean inequalities for scalars and matrices, in this article, we generalize the scalar and matrix inequalities for the difference between…

Functional Analysis · Mathematics 2015-01-21 Wenshi Liao , Junliang Wu

We prove new inequalities for the spectral radius, essential spectral radius, operator norm, measure of noncompactness and numerical radius of Hadamard weighted geometric means of positive kernel operators on Banach function and sequence…

Functional Analysis · Mathematics 2022-02-01 Katarina Bogdanović , Aljoša Peperko

We prove mixed inequalities for the Hardy-Littlewood maximal function $M^{\rho,\sigma}$, where $\rho$ is a critical radius function and $\sigma\geq 0$. We also exhibit and prove an extension of Cruz-Uribe, Martell and P\'erez extrapolation…

Classical Analysis and ODEs · Mathematics 2024-02-29 Fabio Berra , Gladis Pradolini , Pablo Quijano

We present a general refinement of the Cauchy-Schwarz inequality over complete inner product spaces and show that it can be of interest for some statistical applications. This generalizes and simplifies previous results on the same subject.

Statistics Theory · Mathematics 2024-04-10 Sergio Scarlatti

Let $r_A(T)$ denote the $A$-spectral radius of an operator $T$ which is bounded with respect to the seminorm induced by a positive operator $A$ on a complex Hilbert space $\mathcal{H}$. In this paper, we aim to establish some $A$-spectral…

Functional Analysis · Mathematics 2020-02-10 Kais Feki