Numerical range of the Foguel-Halmos operator

被引：1

作者：

Gau, Hwa-Long ^{[1
]}

Wang, Kuo-Zhong ^{[2
]}

Wu, Pei Yuan ^{[2
]}

机构：

[1] Natl Cent Univ, Dept Math, Chungli 32001, Taiwan

[2] Natl Yang Ming Chiao Tung Univ, Dept Appl Math, Hsinchu 30010, Taiwan

来源：

STUDIA MATHEMATICA | 2022年 / 263卷 / 03期

关键词：

numerical range; numerical radius; Foguel operator; Foguel- Halmos operator; NORM;

D O I：

10.4064/sm201020-30-7

中图分类号：

O1 [数学];

学科分类号：

0701 ; 070101 ;

摘要：

FT = [ S* T Abstract. We study properties of the numerical range of the Foguel-Halmos operator ] on $2 circle plus$2, where S is the simple unilateral shift and T = diag(a1, a2, ...) 0 S with a,,, = 1 if n = 3k for some k >= 1 and a,,, = 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).

引用

页码：267 / 292

页数：26

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