摘要
We study properties of the numerical range of the Foguel–Halmos operator FT = [ S0∗ TS] on ℓ2 ⊕ ℓ2, where S is the simple unilateral shift and T = diag(a1, a2, . . .) with an = 1 if n = 3k for some k ≥ 1 and an = 0 otherwise. Among other things, we show that the numerical range W(FT ) is neither open nor closed, and give lower and upper bounds for the numerical radius w(FT ).
原文 | ???core.languages.en_GB??? |
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頁(從 - 到) | 267-292 |
頁數 | 26 |
期刊 | Studia Mathematica |
卷 | 263 |
發行號 | 3 |
DOIs | |
出版狀態 | 已出版 - 2022 |