English

Reverses and variations of Heinz inequality

Functional Analysis 2015-11-09 v1 Operator Algebras

Abstract

Let A,BA, B be positive definite n×nn\times n matrices. We present several reverse Heinz type inequalities, in particular \begin{align*} \|AX+XB\|_2^2+ 2(\nu-1) \|AX-XB\|_2^2\leq \|A^{\nu}XB^{1-\nu}+A^{1-\nu}XB^{\nu}\|_2^2, \end{align*} where XX is an arbitrary n×nn \times n matrix, 2\|\cdot\|_2 is Hilbert-Schmidt norm and ν>1\nu>1. We also establish a Heinz type inequality involving the Hadamard product of the form \begin{align*} 2|||A^{1\over2}\circ B^{1\over2}|||\leq|||A^{s}\circ B^{1-t}+A^{1-s}\circ B^{t}||| \leq\max\{|||(A+B)\circ I|||,|||(A\circ B)+I|||\}, \end{align*} in which s,t[0,1]s, t\in [0,1] and |||\cdot||| is a unitarily invariant norm.

Keywords

Cite

@article{arxiv.1405.0164,
  title  = {Reverses and variations of Heinz inequality},
  author = {Mojtaba Bakherad and Mohammad Sal Moslehian},
  journal= {arXiv preprint arXiv:1405.0164},
  year   = {2015}
}

Comments

10 pages, to appear in Linear Multilinear Algebra