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In this article, we prove that convex functions and log-convex functions obey certain general refinements that lead to several refinements and reverses of well known inequalities for matrices, including Young's inequality, Heinz inequality,…

Functional Analysis · Mathematics 2016-06-28 Mohammad Sababheh

In this paper, we introduce the notion of conditional $h$-convex functions and we prove an operator version of the Jensen inequality for conditional $h$-convex functions. Using this type of functions, we give some refinements for Ky-Fan's…

Functional Analysis · Mathematics 2022-10-11 Ismail Nikoufar , Davuod Saeedi

Let $D$ be a convex subset of a real vector space. It is shown that a radially lower semicontinuous function $f: D\to \mathbf{R}\cup \{+\infty\}$ is convex if and only if for all $x,y \in D$ there exists $\alpha=\alpha(x,y) \in (0,1)$ such…

Classical Analysis and ODEs · Mathematics 2017-09-26 Paolo Leonetti

It is well known that the traditional Jensen inequality is proved by lower bounding the given convex function, $f(x)$, by the tangential affine function that passes through the point $(E\{X\},f(E\{X\}))$, where $E\{X\}$ is the expectation…

Information Theory · Computer Science 2023-05-17 Neri Merhav

The purpose of this paper is to introduce the logarithmic mean of two convex functionals that extends the logarithmic mean of two positive operators. Some inequalities involving this functional mean are discussed as well. The operator…

Functional Analysis · Mathematics 2020-10-07 Mustapha Raïssouli , Shigeru Furuichi

A considerable amount of literature in the theory of inequality is devoted to the study of Jensen's and Young's inequality. This article presents a number of new inequalities involving the log-convex functions and the geometrically convex…

Classical Analysis and ODEs · Mathematics 2022-02-10 Shigeru Furuichi , Hamid Reza Moradi , Supriyo Dutta

We study a special class of non-convex functions which appear in nonlinear elasticity; and we prove that they have well-defined Legandre transforms. Several examples are given, and an application to a nonlinear eigenvalue problem

Optimization and Control · Mathematics 2007-05-23 Ivar Ekeland

In this paper we first introduce the Heron and Heinz means of two convex functionals. Afterwards, some inequalities involving these functional means are investigated. The operator versions of our theoretical functional results are…

Functional Analysis · Mathematics 2018-12-20 Mustapha Raïssouli , Shigeru Furuichi

Let $\mathbb{B}_J(\mathcal H)$ denote the set of self-adjoint operators acting on a Hilbert space $\mathcal{H}$ with spectra contained in an open interval $J$. A map $\Phi\colon\mathbb{B}_J(\mathcal H)\to {\mathbb B}(\mathcal H)_\text{sa} $…

Functional Analysis · Mathematics 2021-07-23 Frank Hansen , Mohammad Sal Moslehian , Hamed Najafi

We establish in this paper some inequalities for analytic and convex functions on an open interval and positive normalized functionals defined on a Hermitian unital Banach *-algebra. Reverses and refinements of Jensen's and Slater's type…

Functional Analysis · Mathematics 2016-12-20 Silvestru Sever Dragomir

In this paper we point out a converse result of the celebrated Jensen inequality for differentiable convex mappings of several variables and apply it to counterpart well-known analytic inequalities. Applications to Shannon's and Renyi's…

Classical Analysis and ODEs · Mathematics 2007-05-23 Sever Silvestru Dragomir

We characterize real functions $f$ on an interval $(-\alpha,\alpha)$ for which the entrywise matrix function $[a_{ij}] \mapsto [f(a_{ij})]$ is positive, monotone and convex, respectively, in the positive semidefiniteness order. Fractional…

Functional Analysis · Mathematics 2007-10-09 Fumio Hiai

In this paper we associate with an infinite family of real extended functions defined on a locally convex space, a sum, called robust sum, which is always well-defined. We also associate with that family of functions a dual pair of problems…

Optimization and Control · Mathematics 2018-11-07 Nguyen Dinh , Miguel A. Goberna , Michel Volle

We define in the space of n by m matrices of rank n, n less or equal than m, the condition Riemannian structure as follows: For a given matrix A the tangent space of A is equipped with the Hermitian inner product obtained by multiplying the…

Numerical Analysis · Mathematics 2010-07-12 Carlos Beltrán , Jean-Pierre Dedieu , Gregorio Malajovich , Mike Shub

A subequation on an open subset $X\subset \mathbb R^n$ is a subset $F$ of the space of $2$-jets on $X$ with certain properties. A smooth function is said to be $F$-subharmonic if all of its $2$-jets lie in $F$, and using the viscosity…

Analysis of PDEs · Mathematics 2021-05-13 Julius Ross , David Witt Nyström

In this paper, some Jensen's type inequalities between quaternionic bounded selfadjoint operators on quaternionic Hilbert spaces are proved, using a log-convex function. Also, by applying a specific log-convex function, some particular…

Functional Analysis · Mathematics 2025-04-17 Massoumeh Fashandi

We investigate how the type of Convexity of the Core function affects the Csisz\'{a}r $f$-divergence functional. A general treatment for the type of convexity has been considered and the associated perspective functions have been studied.…

Information Theory · Computer Science 2021-01-11 Mohsen Kian

For any given partial order in a $d$-dimensional euclidean space, under mild regularity assumptions, we show that the intersection of closed (generalized) intervals containing more than 1/2 of the probability mass, is a non-empty compact…

Statistics Theory · Mathematics 2012-11-05 Djordje Baljozovic , Milan Merkle

We prove a condition on f \in C^2(\R+,\R) for the convexity of (f o det) on PSym(n), namely that f o det is convex on PSym(n) if and only if f"(s)+(n-1)/(ns) f'(s) >= 0 and f'(s)<= 0 \forall s \in \R+. This generalizes the observation that…

Mathematical Physics · Physics 2012-09-26 Stephan Lehmich , Patrizio Neff , Johannes Lankeit

In this paper we give an integral representation of an $n$-convex function $f$ in general case without additional assumptions on function $f$. We prove that any $n$-convex function can be represented as a sum of two $(n+1)$-times monotone…

Classical Analysis and ODEs · Mathematics 2010-08-17 Teresa Rajba