Lemos–Soares singular-value log-majorization conjecture

Let AA and BB be positive semi-definite matrices, let r,sRr,s\in\mathbb{R}, and for 0t10\leq t\leq1 define the generalized weighted geometric mean by

Ar,tB=Ar/2(A1/2BA1/2)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,B0A,B\geq0, r,sRr,s\in\mathbb{R}, and 0t10\leq t\leq1, then

s((Ar,tB)(As,1tB))logs(Ar+s1B).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.

Sources & referencesView supporting material

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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