Numerical ranges of Foguel operators

Hwa Long Gau, Kuo Zhong Wang, Pei Yuan Wu

研究成果: 雜誌貢獻期刊論文同行評審

摘要

We study properties of the numerical ranges of Foguel operators [Formula presetend], where S is the simple unilateral shift and T is some operator, both acting on ℓ2. Among other things, we show that (1) if T is nonzero compact, then the numerical radius w(FT) is strictly less than 1+(‖T‖/2), (2) if T is a diagonal unitary operator, then 5/2<w(FT)≤3/2, and (3) if T is a scalar operator aI, then the numerical range W(FT) is open and is not a circular disc unless a=0.

原文???core.languages.en_GB???
頁(從 - 到)766-784
頁數19
期刊Linear Algebra and Its Applications
610
DOIs
出版狀態已出版 - 1 2月 2021

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