A new proof of Lee's conjecture on the Frobenius norm via the matrix Cauchy-Schwarz inequality

Fuente: arXiv
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Autore principale: Zhang, Teng
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Pubblicazione: 2025
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author Zhang, Teng
author_facet Zhang, Teng
contents In 2010, Eun-Young Lee conjectured that if $A,B$ are two $n\times n$ complex matrices and $\left|A\right|, \left|B\right|$ are the absolute values of $A, B$, respectively, then \[ \|A+B\|_F\le \sqrt{\dfrac{1+\sqrt{2}}{2}}\|\left|A\right|+\left|B\right|\|_F, \] where $\|\cdot\|_F$ is the Frobenius norm of matrices. This conjecture has been proven by Lin and Zhang [J. Math. Anal. Appl. 516 (2022) 126542] by studying inequalities for the angle between two matrices induced by the Frobenius inner product. In this paper, we present a new proof of the same result, relying solely on the Cauchy-Schwarz inequality.
format Preprint
id arxiv_https___arxiv_org_abs_2507_02684
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A new proof of Lee's conjecture on the Frobenius norm via the matrix Cauchy-Schwarz inequality
Zhang, Teng
Functional Analysis
15A60, 47A30
In 2010, Eun-Young Lee conjectured that if $A,B$ are two $n\times n$ complex matrices and $\left|A\right|, \left|B\right|$ are the absolute values of $A, B$, respectively, then \[ \|A+B\|_F\le \sqrt{\dfrac{1+\sqrt{2}}{2}}\|\left|A\right|+\left|B\right|\|_F, \] where $\|\cdot\|_F$ is the Frobenius norm of matrices. This conjecture has been proven by Lin and Zhang [J. Math. Anal. Appl. 516 (2022) 126542] by studying inequalities for the angle between two matrices induced by the Frobenius inner product. In this paper, we present a new proof of the same result, relying solely on the Cauchy-Schwarz inequality.
title A new proof of Lee's conjecture on the Frobenius norm via the matrix Cauchy-Schwarz inequality
topic Functional Analysis
15A60, 47A30
url https://arxiv.org/abs/2507.02684