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In this work, the mixed Schwarz inequality for semi-Hilbertian space operators is proved. Namely, for every positive Hilbert space operator $A$. If $f$ and $g$ are nonnegative continuous functions on $\left[0,\infty\right)$ satisfying…

Functional Analysis · Mathematics 2020-07-06 Mohammad W. Alomari

In this expository article we collect and discuss some recent results on different consequences of a Sharp Reverse H\"older Inequality for $A_{\infty}$ weights. For two given operators $T$ and $S$, we study $L^p(w)$ bounds of…

Classical Analysis and ODEs · Mathematics 2012-04-10 Carmen Ortiz-Caraballo , Carlos Pérez , Ezequiel Rela

We give another proof of a result of Bennett on the $l^{p}$ operator norms of some weighted mean matrices for the case $p=2$ and we also present some related results.

Functional Analysis · Mathematics 2008-03-11 Peng Gao

We give a refined Young inequality which generalizes the inequality by Zou--Jiang. We also show the upper bound for the logarithmic mean by the use of the weighted geometric mean and the weighted arithmetic mean. Furthermore, we show some…

Classical Analysis and ODEs · Mathematics 2022-03-14 Shigeru Furuichi , Mehdi Eghbali Amlashi

We present some new upper and lower bounds for the numerical radius of bounded linear operators on a complex Hilbert space and show that these are stronger than the existing ones. In particular, we prove that if $A$ is a bounded linear…

Functional Analysis · Mathematics 2024-08-23 Pintu Bhunia , Suvendu Jana , Kallol Paul

Reverse H\"{o}lder inequalities for a class of functions on a probability space constitute an important tool in Analysis in Probability. After revisiting how a (modified) log-Sobolev inequality can be used to derive reverse H\"{o}lder…

Functional Analysis · Mathematics 2020-12-01 Emanuel Milman

Inequalities for product operators on mixed norm Lebesgue spaces and permuted mixed norm Lebesgue spaces are established. They depend only on inequalities for the factors and on the Lebesgue indices involved. Inequalities for the bivariate…

Functional Analysis · Mathematics 2022-01-20 Wayne Grey , Gord Sinnamon

In this paper, we investigate the Mill's ratio estimation problem and get two new inequalities. Compared to the well known results obtained by Gordon, they becomes tighter. Furthermore, we also discuss the inverse Q-function approximation…

Information Theory · Computer Science 2021-06-22 Pingyi Fan

Convergence rates results for Tikhonov regularization of nonlinear ill-posed operator equations in abstract function spaces require the handling of both smoothness conditions imposed on the solution and structural conditions expressing the…

Numerical Analysis · Mathematics 2009-09-29 Radu Ioan Bot , Bernd Hofmann

In this paper the authors show how to use Riemann-Hilbert techniques to prove various results, some old, some new, in the theory of Toeplitz operators and orthogonal polynomials on the unit circle (OPUC's). There are four main results: the…

Functional Analysis · Mathematics 2007-05-23 Percy Deift , Jorgen Ostensson

For initial value problems associated with operator-valued Riccati differential equations posed in the space of Hilbert--Schmidt operators existence of solutions is studied. An existence result known for algebraic Riccati equations is…

Analysis of PDEs · Mathematics 2018-08-06 Monika Eisenmann , Etienne Emmrich , Volker Mehrmann

We present several operator and norm inequalities for Hilbert space operators. In particular, we prove that if $A_{1},A_{2},...,A_{n}\in {\mathbb B}({\mathscr H})$, then…

Functional Analysis · Mathematics 2011-01-21 M. Erfanian Omidvar , M. S. Moslehian , A. Niknam

We employ the pinching theorem, ensuring that some operators A admit any sequence of contractions as an operator diagonal of A, to deduce/improve two recent theorems of Kennedy-Skoufranis and Loreaux-Weiss for conditional expectations onto…

Functional Analysis · Mathematics 2015-05-12 Jean-Christophe Bourin , Eun-Young Lee

We prove a sharp integral inequality valid for non-negative functions defined on $[0,1]$, with given $L^1$ norm. This is in fact a generalization of the well known integral Hardy inequality. We prove it as a consequence of the respective…

Functional Analysis · Mathematics 2014-12-09 Eleftherios N. Nikolidakis

Some new characterizations of nonnegative Hamiltonian operator matrices are given. Several necessary and sufficient conditions for an unbounded nonnegative Hamiltonian operators to be invertible are obtained; so that the main results in the…

Functional Analysis · Mathematics 2013-09-17 Guohai Jin , Guolin Hou , Alatancang Chen , Deyu Wu

Some additive reverses of the generalised triangle inequality in normed linear spaces are given. Applications for complex numbers are provided as well.

Metric Geometry · Mathematics 2016-09-07 Sever Silvestru Dragomir

This article introduces several new relations among related Hilbert space operators. In particular, we prove some L\"{o}ewner partial orderings among $T, |T|, \mathcal{R}T, \mathcal{I}T, |T|+|T^*|$ and many other related forms, as a new…

Functional Analysis · Mathematics 2023-03-08 Mohammad Sababheh , Hamid Reza Moradi

In this note, we provide some sufficient and necessary conditions for the core inverse of the perturbed operator to have the simplest possible expression. The results improve the recent work by H. Ma (Optimal perturbation bounds for the…

Functional Analysis · Mathematics 2018-07-05 Qianglian Huang , Saijie Chen , Lanping Zhu

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

We present a stability version of H\"older's inequality, incorporating an extra term that measures the deviation from equality. Applications are given.

Classical Analysis and ODEs · Mathematics 2009-10-30 J. M. Aldaz