Lemos–Soares singular-value log-majorization conjecture

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Let AA and BB be positive semi-definite matrices, let r,s∈Rr,s\in\mathbb{R}, and for 0≤t≤10\leq t\leq1 define the generalized weighted geometric mean by

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 s(X)s(X) denote the vector of singular values of XX, arranged in decreasing order, and let ≺log⁡\prec_{\log} denote log-majorization.

Lemos–Soares conjecture. If A,B≥0A,B\geq0, r,s∈Rr,s\in\mathbb{R}, and 0≤t≤10\leq t\leq1, then

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

This conjecture asks for a singular-value analogue of a previously known eigenvalue log-majorization inequality. The supplied status evidence indicates that it has been resolved, although the resolving result is not identified 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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