Zhang's quasisymmetric modulus conjecture

From papers

For ZMdZ\in\mathbb{M}_d, let Zqsym|Z|_{\mathrm{qsym}} denote the quasisymmetric modulus used in Zhang's conjecture. For A,BMdA,B\in\mathbb{M}_d, there are unitaries U,VMdU,V\in\mathbb{M}_d. Zhang's quasisymmetric modulus conjecture.

A+Bqsym2(UAqsymU+VBqsymV).|A+B|_{\mathrm{qsym}}\le\sqrt{2}\left(U|A|_{\mathrm{qsym}}U^*+V|B|_{\mathrm{qsym}}V^*\right).

This is described as a related strong conjecture proposed by Zhang; the supplied text gives no resolution status.

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Sources & referencesView supporting material

Primary source

Jean-Christophe Bourin and Eun-Young Lee, “Averages over matrix unitary orbits and spectral order”, arXiv:2606.15624 (2026).

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