研究了$2\times 2$上三角算子矩阵的四类点谱扰动. 基于空间分解技巧和对点谱, 剩余谱的细分,得到了$2\times 2$上三角算子矩阵的四类点谱可由其对角元素表示的充分必要条件.

Perturbation of four kinds of point spectrum of 2 × 2 upper triangular operator matrices is studied. Based on the space decomposition technique and the
subdivision of point spectrum and residual spectrum, a necessary and sufficient con- dition of pi(MC) = pi(A) ∪ pi(B) (i = 1, 2, 3, 4) for every bounded operator C is obtainedn by using its diagonal elements.