论文标题
$ L（h）$的数值半径规范和极端收缩
Numerical radius norm and extreme contractions of $L(H)$
论文作者
论文摘要
假设$ l（h）$是所有有界线性操作员在复杂的希尔伯特空间上的空间。 $ l（h）。此外，就数值半径规范而言，有$ h $的非独立运营商是极端的收缩。
Suppose $L(H)$ is the space of all bounded linear operators on a complex Hilbert space $H.$ This article deals with the problem of characterizing the extreme contractions of $L(H)$ with respect to the numerical radius norm on $L(H).$ In contrast to the usual operator norm, it is proved that there exists a class of unitary operators on $H$ which are not extreme contractions when the numerical radius norm is considered on $L(H).$ Moreover, there are non-unitary operators on $H$ which are extreme contractions as far as the numerical radius norm is concerned.
