Generalized eigenvalue log-majorization conjecture for geometric means

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Let A,B≥0A,B\geq0, let r,s∈Rr,s\in\mathbb{R}, and for 0≤t≤10\leq t\leq1 define

A♯r,tB=Ar/2(A−1/2BA−1/2)tAr/2.A\sharp_{r,t}B=A^{r/2}(A^{-1/2}BA^{-1/2})^tA^{r/2}.

Let λ(X)\lambda(X) denote the vector of eigenvalues of XX, arranged in decreasing order, and let ≺log⁡\prec_{\log} denote log-majorization.

Generalized geometric-mean conjecture. If 0≤t≤10\leq t\leq1, p≥1p\geq1, and either r,s≥1r,s\geq1 or r,s≤0r,s\leq0, then

λ((A♯r,tB)p(A♯s,1−tB)p)≺log⁡λ(Ap(r+s−1)Bp).\lambda\left((A\sharp_{r,t}B)^p(A\sharp_{s,1-t}B)^p\right)\prec_{\log}\lambda\left(A^{p(r+s-1)}B^p\right).

The claim extends the paper’s established cases for restricted ranges of p,r,s,tp,r,s,t. No resolution is supplied in the provided text.

References

Primary source

Mohammad M. Ghabries, Hassane Abbas, Bassam Mourad and Abdallah Assi, “New log-majorization results concerning eigenvalues and singular values and a complement of a norm inequality”, arXiv:2105.13356 (2021).

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