Various inequalities between quasi-arithmetic mean and quasi-geometric type means for matrices

Fuente: arXiv
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Main Author: Hiai, Fumio
Format: Preprint
Published: 2025
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author Hiai, Fumio
author_facet Hiai, Fumio
contents In this paper, for $0<α<1$, $p>0$ and positive semidefinite matrices $A,B\ge0$, we consider the quasi-extension $\mathcal{A}_{α,p}(A,B):=((1-α)A^p+αB^p)^{1/p}$ of the $α$-weighted arithmetic matrix mean, and the quasi-extensions $\mathcal{M}_{α,p}(A,B):=\mathcal{M}_α(A^p,B^p)^{1/p}$ of several different $α$-weighted geometric-type matrix means $\mathcal{M}_α(A,B)$ such as the $α$-weighted geometric mean in Kubo and Ando's sense and two types of $α$-weighted version of Fiedler and Pták's spectral geometric mean, as well as the Rényi mean and the $α$-weighted Log-Euclidean mean. For these we examine the inequalities $\mathcal{A}_{α,p}(A,B)\triangleleft\mathcal{A}_{α,q}(A,B)$ and $\mathcal{M}_{α,p}(A,B)\triangleleft\mathcal{A}_{α,q}(A,B)$ of arithmetic-geometric type, where $\triangleleft$ is one of several different matrix orderings varying from the strongest Loewner order to the weakest order determined by trace inequality. For each choice of the above inequalities, our goal is to hopefully obtain the necessary and sufficient condition on $p,q,α$ under which the inequality holds for all $A,B\ge0$.
format Preprint
id arxiv_https___arxiv_org_abs_2508_20309
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Various inequalities between quasi-arithmetic mean and quasi-geometric type means for matrices
Hiai, Fumio
Functional Analysis
15A45, 47A64
In this paper, for $0<α<1$, $p>0$ and positive semidefinite matrices $A,B\ge0$, we consider the quasi-extension $\mathcal{A}_{α,p}(A,B):=((1-α)A^p+αB^p)^{1/p}$ of the $α$-weighted arithmetic matrix mean, and the quasi-extensions $\mathcal{M}_{α,p}(A,B):=\mathcal{M}_α(A^p,B^p)^{1/p}$ of several different $α$-weighted geometric-type matrix means $\mathcal{M}_α(A,B)$ such as the $α$-weighted geometric mean in Kubo and Ando's sense and two types of $α$-weighted version of Fiedler and Pták's spectral geometric mean, as well as the Rényi mean and the $α$-weighted Log-Euclidean mean. For these we examine the inequalities $\mathcal{A}_{α,p}(A,B)\triangleleft\mathcal{A}_{α,q}(A,B)$ and $\mathcal{M}_{α,p}(A,B)\triangleleft\mathcal{A}_{α,q}(A,B)$ of arithmetic-geometric type, where $\triangleleft$ is one of several different matrix orderings varying from the strongest Loewner order to the weakest order determined by trace inequality. For each choice of the above inequalities, our goal is to hopefully obtain the necessary and sufficient condition on $p,q,α$ under which the inequality holds for all $A,B\ge0$.
title Various inequalities between quasi-arithmetic mean and quasi-geometric type means for matrices
topic Functional Analysis
15A45, 47A64
url https://arxiv.org/abs/2508.20309