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arXiv 1507.01418math.FA
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巴拿赫空间上算子数值域的半群方法

A semigroup approach to the numerical range of operators on Banach spaces

Martin Adler, Waed Dada, Agnes Radl

摘要:

在Banach空间$X$上引入了(无界)线性算子$A$的数值谱$σ_n(A)\subset \mathbb{C}$,并研究了它的性质.我们的定义与$A$的数值域$W(A)$密切相关,并且总是产生$W(A)$的超集。在希尔伯特空间上的有界算子的情况下,这两个概念是一致的。然而,与数值域不同,$σ_n(A)$总是封闭的、凸的并且包含$A$的谱。在本文中,我们着重强调我们的方法与$C_0$ -半群理论的联系。

英文摘要:

We introduce the numerical spectrum $σ_n(A)\subset \mathbb{C}$ of an (unbounded) linear operator $A$ on a Banach space $X$ and study its properties. Our definition is closely related to the numerical range $W(A)$ of $A$ and always yields a superset of $W(A)$. In the case of bounded operators on Hilbert spaces, the two notions coincide. However, unlike the numerical range, $σ_n(A)$ is always closed, convex and contains the spectrum of $A$. In the paper we strongly emphasise the connection of our approach to the theory of $C_0$-semigroups.

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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