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Refinements of a reversed AM-GM operator inequality

Functional Analysis 2017-10-10 v1 Operator Algebras

Abstract

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 B^{-1})\right)\leq\alpha^p\Phi^p\left(A\sharp_\nu B\right), \end{eqnarray*} where A,BA,B are positive operators on a Hilbert space such that 0<mA,BM0<m \leq A, B \leq M for some positive numbers m,Mm, M, Φ\Phi is a positive unital linear map, ν[0,1]\nu\in[0,1], r=min{ν,1ν}r=\min\{\nu,1-\nu\}, p>0p>0 and α=max{(M+m)24Mm,(M+m)242pMm}\alpha=\max\left\{\frac{(M+m)^2}{4Mm},\frac{(M+m)^2}{4^\frac{2}{p}Mm}\right\}.

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Cite

@article{arxiv.1506.06414,
  title  = {Refinements of a reversed AM-GM operator inequality},
  author = {Mojtaba Bakherad},
  journal= {arXiv preprint arXiv:1506.06414},
  year   = {2017}
}

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11 pages