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Let $A,B\in \mathbb{B}(\mathscr{H})$ be such that $0<b_{1}I \leq A \leq a_{1}I$ and $0<b_{2}I \leq B \leq a_{2}I$ for some scalars $0<b_{i}< a_{i},\;\; i=1,2$ and $\Phi:\mathbb{B}(\mathscr{H})\rightarrow\mathbb{B}(\mathscr{K})$ be a…

Functional Analysis · Mathematics 2012-05-21 R. Kaur , M. Singh , J. S. Aujla , M. S. Moslehian

The purpose of this paper is to present some general inequalities for operator concave functions which include some known inequalities as a particular case. Among other things, we prove that if $A\in \mathcal{B}\left( \mathcal{H} \right)$…

Functional Analysis · Mathematics 2018-03-01 S. Sheybani , M. E. Omidvar , H. R. Moradi

In this paper we show that for a non-negative operator monotone function $f$ on $[0, \infty)$ such that $f(0)= 0$ and for any positive semidefinite matrices $A$ and $B$, $$ Tr((A-B)(f(A)-f(B))) \le Tr(|A-B|f(|A-B|)). $$ When the function…

Functional Analysis · Mathematics 2019-04-04 Trung Hoa Dinh , Minh Toan Ho , Cong Trinh Le , Bich Khue Vo

Let $f$ be an operator convex function on $(0,\infty)$, and $\Phi$ be a unital positive linear maps on $B(H)$. we give a complementary inequality to Davis-Choi-Jensen's inequality as follows \begin{equation*} f(\Phi(A))\geq…

Functional Analysis · Mathematics 2021-05-11 A. G. Ghazanfari

If $\sigma$ is a symmetric mean and $f$ is an operator monotone function on $[0, \infty)$, then $$f(2(A^{-1}+B^{-1})^{-1})\le f(A\sigma B)\le f((A+B)/2).$$ Conversely, Ando and Hiai showed that if $f$ is a function that satisfies either one…

Functional Analysis · Mathematics 2018-03-20 Trung Hoa Dinh , Raluca Dumitru , Jose Franco

We show that the symmetrized product $AB+BA$ of two positive operators $A$ and $B$ is positive if and only if $f(A+B)\leq f(A)+f(B)$ for all non-negative operator monotone functions $f$ on $[0,\infty)$ and deduce an operator inequality. We…

Functional Analysis · Mathematics 2012-03-21 M. S. Moslehian , H. Najafi

In this note, some inequalities involving operator means of sectorial matrices are proved which are generalizations and refinements of previous known results. Among them, let $A$ and $B$ be two accretive matrices with…

Functional Analysis · Mathematics 2023-05-09 M. Khosravi , A. Sheikhhosseini , S. Malekinejad

We prove some refinements of a reverse AM-GM operator inequality due to M. Lin [Studia Math. 2013;215:187-194]. In particular, we show the operator inequality \begin{eqnarray*} \Phi^p\left(A\nabla_\nu B+2rMm(A^{-1}\nabla B^{-1}-A^{-1}\sharp…

Functional Analysis · Mathematics 2017-10-10 Mojtaba Bakherad

We improve and generalize some operator inequalities for positive linear maps. It is shown, among other inequalities, that if $0<m\le B\le m'<M'\le A\le M$ or $0<m\le A\le m'<M'\le B\le M$, then for each $2\le p<\infty $ and $\nu \in \left[…

Functional Analysis · Mathematics 2017-07-25 H. R. Moradi , M. E. Omidvar , I. H. Gümüş , R. Naseri

We prove that a continuous function $f:(0,\infty) \to (0,\infty)$ is operator monotone increasing if and only if $f(A \: !_t \: B) \leqs f(A) \: !_t \: f(B)$ for any positive operators $A,B$ and scalar $t \in [0,1]$. Here, $!_t$ denotes the…

Functional Analysis · Mathematics 2015-06-24 Pattrawut Chansangiam

Employing the notion of operator log-convexity, we study joint concavity$/$ convexity of multivariable operator functions: $(A,B)\mapsto F(A,B)=h\left[ \Phi(f(A))\ \sigma\ \Psi(g(B))\right]$, where $\Phi$ and $\Psi$ are positive linear maps…

Functional Analysis · Mathematics 2021-03-05 Mohsen Kian , Yuki Seo

For positive definite matrices $A$ and $B$, the Kubo-Ando matrix power mean is defined as $$ P_\mu(p, A, B) = A^{1/2}\left(\frac{1+(A^{-1/2}BA^{-1/2})^p}{2}\right )^{1/p} A^{1/2}\quad (p \ge 0). $$ In this paper, for $0\le p \le 1 \le q$,…

Functional Analysis · Mathematics 2021-07-14 Trung Hoa Dinh , Cong Trinh Le , The Van Nguyen , Bich Khue Vo

Let $A$ be a positive definite operator on a Hilbert space $H$, and $|||.|||$ be a unitarily invariant norm on $B(H)$. We show that if $f$ is an operator monotone function on $(0,\infty)$ and $n\in \mathbb{N}$, then $|||D^n…

Functional Analysis · Mathematics 2021-05-13 Amir Ghasem Ghazanfari

Let f be a non-negative concave function on the positive half-line. Let A and B be two positive matrices. Then, for all symmetric norms, || f(A+B) || is less than || f(A)+f(B) ||. When f is operator concave, this was proved by Ando and…

Functional Analysis · Mathematics 2007-05-23 Jean-Christophe Bourin , Mitsuru Uchiyama

Let $\Phi$ be a unital positive linear map and let $A$ be a positive invertible operator. We prove that there exist partial isometries $U$ and $V$ such that \[ |\Phi(f(A))\Phi(A)\Phi(g(A))|\leq U^*\Phi(f(A)Ag(A))U \] and…

Functional Analysis · Mathematics 2021-07-23 Mohsen Kian , M. S. Moslehian , R. Nakamoto

Motivated by some recently established operator Jensen-type inequalities related to a usual convexity, in the present paper we derive several more accurate operator Jensen-type inequalities for certain subclasses of convex functions. More…

Functional Analysis · Mathematics 2018-05-11 Mojtaba Bakherad , Mohsen Kian , Mario Krnic , Seyyed Alireza Ahmadi

Recently the behavior of operator monotone functions on unbounded intervals with respect to the relation of strictly positivity has been investigated. In this paper we deeply study such behavior not only for operator monotone functions but…

Functional Analysis · Mathematics 2017-09-26 M. Fujii , M. S. Moslehian , H. Najafi , R. Nakamoto

We present some operator inequalities for positive linear maps that generalize and improve the derived results in some recent years. For instant, if $A$ and $B$ are positive operators and $m,m^{'},M,M^{'}$ are positive real numbers…

Functional Analysis · Mathematics 2018-01-09 Leila Nasiri , Mojtaba Bakherad

Let $p$ be a positive number and $h$ a function on $\mathbb{R}^+$ satisfying $h(xy) \ge h(x) h(y)$ for any $x, y \in \mathbb{R}^+$. A non-negative continuous function $f$ on $K (\subset \mathbb{R}^+)$ is said to be {\it operator…

Functional Analysis · Mathematics 2017-12-22 Trung Hoa Dinh , Khue TB Vo

We present some reverse Young-type inequalities for the Hilbert-Schmidt norm as well as any unitarily invariant norm. Furthermore, we give some inequalities dealing with operator means. More precisely, we show that if $A, B\in {\mathfrak…

Functional Analysis · Mathematics 2021-07-23 Mojtaba Bakherad , Mario Krnic , Mohammad Sal Moslehian
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