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We study arbitrary order symmetry operators for the linear Schr\"odinger equations with arbitrary number of spatial variables. We deduce determining equations for coefficient functions of such operators and consider in detail some cases…

Mathematical Physics · Physics 2016-03-08 A. G. Nikitin

The purpose of this article is to study Bohr inequalities involving the absolute values of the coefficients of an operator valued function. To be more specific, we establish an operator valued analogue of a classical result regarding the…

Complex Variables · Mathematics 2020-03-13 Bappaditya Bhowmik , Nilanjan Das

For operators representing ill-posed problems, an ordering by ill-posedness is proposed, where one operator is considered more ill-posed than another one if the former can be expressed as a cocatenation of bounded operators involving the…

Functional Analysis · Mathematics 2025-02-06 Stefan Kindermann , Bernd Hofmann

In this article, we explore the celebrated Gr\"{u}ss inequality, where we present a new approach using the Gr\"{u}ss inequality to obtain new refinements of operator means inequalities. We also present several operator Gr\"{u}ss-type…

Functional Analysis · Mathematics 2020-09-17 H. R. Moradi , S. Furuichi , Z. Heydarbeygi , M. Sababheh

In this paper, we generalize several Berezin number inequalities involving product of operators. For instance, we show that if $A, B$ are positive operators and $X$ is any operator, then \begin{align*}…

Functional Analysis · Mathematics 2018-05-22 Monire Hajmohamadi , Rahmatollah Lashkaripour , Mojtaba Bakherad

In this paper, we study operator mean inequalities for the weighted arithmetic, geometric and harmonic means. We give a slight modification of Audenaert's result to show the relation between Kwong functions and operator monotone functions.…

Functional Analysis · Mathematics 2024-05-10 Nahid Gharakhanlu , Mohammad Sal Moslehian , Hamed Najafi

The difficulty for solving ill-posed linear operator equations in Hilbert space is reflected by the strength of ill-posedness of the governing operator, and the inherent solution smoothness. In this study we focus on the ill-posedness of…

Numerical Analysis · Mathematics 2025-01-24 Peter Mathé , Bernd Hofmann

Tsallis relative operator entropy is defined and then its properties are given. Shannon inequality and its reverse one in Hilbert space operators derived by T.Furuta \cite{Fu:par} are extended in terms of the parameter of the Tsallis…

Functional Analysis · Mathematics 2007-05-23 Kenjiro Yanagi , Ken Kuriyama , Shigeru Furuichi

In this paper, we introduce the concept of operator arithmetic-geometrically convex functions for positive linear operators and prove some Hermite-Hadamard type inequalities for these functions. As applications, we obtain trace inequalities…

Functional Analysis · Mathematics 2016-03-16 Ali Taghavi , Vahid Darvish , Haji Mohammad Nazari

Let $n\in\mathbb{N}$ and let $A$ be a closed linear operator (everywhere bounded or unbounded). In this paper, we study (among others) equations of the type $A^*A=A^n$ where $n\geq2$ and see when they yield $A=A^*$ (or a weaker class of…

Functional Analysis · Mathematics 2019-02-07 Souheyb Dehimi , Mohammed Hichem Mortad , Zsigmond Tarcsay

In this paper we introduce a very general setting dealing with the superposition of operators of any positive order and provide a systematic study of them. We also provide examples and counterexamples, as well as characterizing properties…

Analysis of PDEs · Mathematics 2025-10-10 Serena Dipierro , Sven Jarohs , Enrico Valdinoci

We give an upper bound for the weighted geometric mean using the weighted arithmetic mean and the weighted harmonic mean. We also give a lower bound for the weighted geometric mean. These inequalities are proven for two invertible positive…

Functional Analysis · Mathematics 2014-10-21 Shigeru Furuichi

In this paper, we present generalized P\'olya-Szeg\"o type inequalities for positive invertible operators on a Hilbert space for arbitrary operator means between the arithmetic and the harmonic means. As applications, we present Operator…

Functional Analysis · Mathematics 2020-01-07 Trung Hoa Dinh , Hamid Reza Moradi , Mohammad Sababheh

The detailed construction of the general solution of a second order non-homogenous linear operatordifference equation is presented. The wide applicability of such an equation as well as the usefulness of its resolutive formula is shown by…

Mathematical Physics · Physics 2008-04-18 M. A. Jivulescu , A. Napoli , A. Messina

We give a general formulation of Jensen's operator inequality for unital fields of positive linear mappings, and we consider different types of converse inequalities.

Operator Algebras · Mathematics 2008-08-11 Frank Hansen , Josip Pecaric , Ivan Peric

We study the Mercer inequality and its operator extension for superquadratic functions. In particular, we give a more general form of the Mercer inequality by replacing some constants by positive operators. As some consequences, our results…

Functional Analysis · Mathematics 2024-03-27 Mohsen Kian , Zainab Peymani Mazraj

We develop an operator approach to the integration of linear differential equations based on intertwining relations between differential operators. Conditions for the existence of intertwining operators are obtained, and it is shown that,…

Mathematical Physics · Physics 2026-02-17 O. V. Kaptsov

Assume that $p > 1$ and $p - 1 \le \alpha \le p$ are real numbers and $\Omega$ is a non-empty open subset of ${\mathbb R}^n$, $n \ge 2$. We consider the inequality $$ {\rm div} \, A (x, D u) + b (x) |D u|^\alpha \ge 0, $$ where $D =…

Analysis of PDEs · Mathematics 2019-04-09 A. A. Kon'kov

In this paper, we establish some upper bounds for Berezin number inequalities including of $2\times 2$ operator matrices and their off-diagonal parts. Among other inequalities, it is shown that if $T=\left[\begin{array}{cc} 0&X, Y&0…

Functional Analysis · Mathematics 2023-01-18 Mojtaba Bakherad , Monire Hajmohamadi , Rahmatollah Lashkaripour , Satyajit Sahoo

In this paper, we establish a fundamental inequality for fourth order partial differential operator $\cal P=\alpha\partial_s+\beta\partial_{ss}+\Delta^2$ ($\alpha, \beta\in\mathbb{R}$) with an abstract exponential-type weight function. Such…

Analysis of PDEs · Mathematics 2022-04-19 Yan Cui , Xiaoyu Fu , Jiaxin Tian