论文标题
在某些操作员和矩阵的邮票上
On the Stampfli point of some operators and matrices
论文作者
论文摘要
Stampfli在他的Pacific J. Math（1970）论文中介绍了操作员$ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a。我们得出了一些有关几类运算符的ST（$ a $）位置的结果，包括具有标量对角线块的2 by-2块操作员矩阵和带有重复特征值的3 by-3矩阵。我们还表明，对于几乎正常的$ a $，其Stampfli点就在于频谱的凸面船体，总体上并非如此。建立了属性ST（$ a $）= 0与身份运营商的Roberts正交性之间的某些关系。
The center of mass of an operator $A$ (denoted St($A$), and called in this paper as the {\em Stampfli point} of A) was introduced by Stampfli in his Pacific J. Math (1970) paper as the unique $λ\in\mathbb C$ delivering the minimum value of the norm of $A-λI$. We derive some results concerning the location of St($A$) for several classes of operators, including 2-by-2 block operator matrices with scalar diagonal blocks and 3-by-3 matrices with repeated eigenvalues. We also show that for almost normal $A$ its Stampfli point lies in the convex hull of the spectrum, which is not the case in general. Some relations between the property St($A$)=0 and Roberts orthogonality of $A$ to the identity operator are established.
