Norm inequalities related to operator monotone functions
Abstract
Let be a positive definite operator on a Hilbert space , and be a unitarily invariant norm on . We show that if is an operator monotone function on and , then and is a quasi-convex function on the set of all positive definite operators in . We establish some estimates of the right hand side of some Hermite-Hadamard type inequalities in which differentiable functions are involved, and norms of the maps induced by them on the set of self adjoint operators are convex, quasi-convex or -convex. As applications, we obtain some of bounds for in term of . For instance, Let be two operator monotone functions on . Then, for every unitarily invariant norm and every positive definite operators , \begin{align*} &\left|\left|\left|f(A)g(A)-f(B)g(B)\right|\right|\right|\notag\\ &\leq|||B-A|||\Big[\max\left\{\|f'(A)\|,\|f'(B)\|\right\}\times\max\left\{\|g(A)\|,\|g(B)\|\right\}\notag\\ &+\max\left\{\|f(A)\|,\|f(B)\|\right\}\times \max\left\{\|g'(A)\|,\|g'(B)\|\right\}\Big]. \end{align*}
Cite
@article{arxiv.2008.13226,
title = {Norm inequalities related to operator monotone functions},
author = {Amir Ghasem Ghazanfari},
journal= {arXiv preprint arXiv:2008.13226},
year = {2021}
}