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arXiv · 1104.1338

The k-rank numerical radii

Aikaterini Aretaki·John Maroulas
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Abstract

The $k$-rank numerical range $\Lambda_{k}(A)$ is expressed via an intersection of a countable family of numerical ranges $\{F(M^{*}_{\nu}AM_{\nu})\}_{\nu\in\mathbb{N}}$ with respect to $n\times (n-k+1)$ isometries $M_{\nu}$. This implication for $\Lambda_{k}(A)$ provides further elaboration of the $k$-rank numerical radii of $A$.

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Aikaterini Aretaki, John Maroulas. 2011-04-07. The k-rank numerical radii. https://arxiv.org/abs/1104.1338

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