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arXiv · 1901.06759

Submultiplicativity of the numerical radius of commuting matrices of order two

Chi-Kwong Li·Yiu-Tung Poon
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Abstract

Denote by $w(T)$ the numerical radius of a matrix $T$. An elementary proof is given to the fact that $w(AB) \leq w(A)w(B)$ for a pair of commuting matrices of order two, and characterization is given for the matrix pairs that attain the quality.

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Chi-Kwong Li, Yiu-Tung Poon. 2019-01-21. Submultiplicativity of the numerical radius of commuting matrices of order two. https://arxiv.org/abs/1901.06759

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