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arXiv 2402.05360math.FA
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关于半希尔伯特型算子的$A$-数值域的注记

A note on the $A$-numerical range of semi-Hilbertian operators

Anirban Sen, Riddhick Birbonshi, Kallol Paul

AI总结:

本文在半希尔伯特型结构下研究$A$-有界算子的$A$-数值域与$A$-谱的关系,引入$A$-正规算子新定义,证明其数值域闭包为谱的凸包,推广Anderson定理,并引入强$A$-数值闭类。

摘要:

本文在半希尔伯特型结构下探讨$A$-有界算子的$A$-数值域与$A$-谱之间的关系。我们引入了$A$-正规算子的新定义,并证明了$A$-正规算子的$A$-数值域的闭包是$A$-谱的凸包。我们进一步证明了$A$-正规算子与$A$-紧算子之和的Anderson定理,该定理改进并推广了现有关于$A$-紧算子的Anderson定理的结果。最后,我们引入了强$A$-数值闭算子类,并与其他结果一起证明了$A$-正规算子类是强$A$-数值闭的。

英文摘要:

In this paper we explore the relation between the $A$-numerical range and the $A$-spectrum of $A$-bounded operators in the setting of semi-Hilbertian structure. We introduce a new definition of $A$-normal operator and prove that closure of the $A$-numerical range of an $A$-normal operator is the convex hull of the $A$-spectrum. We further prove Anderson's theorem for the sum of $A$-normal and $A$-compact operators which improves and generalizes the existing result on Anderson's theorem for $A$-compact operators. Finally we introduce strongly $A$-numerically closed class of operators and along with other results prove that the class of $A$-normal operators is strongly $A$-numerically closed.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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