算子序列的升标和降标  

THE ASCENT AND DESCENT OF OPERATOR SEQUENCES

作　　者：尹逊汝[1] 刘伟彦[2] 李绍宽[2] 

机构地区：[1]泰山学院数学与系统科学系,山东泰安271021 [2]东华大学理学院,上海200051

出　　处：《数学杂志》2009年第2期167-172,共6页Journal of Mathematics

摘　　要：本文研究了与算子紧序列有关的一类算子序列和算子上半Fredholm序列的升标和降标的一些性质.利用同伦的思想证明了具有有限升标(降标)的算子上半Fredholm序列在其摄动类中交换元的摄动下具有同样性质,从而把单个半Fredholm算子的有关结果推广到算子序列.In this paper, we study some properties of a class of operator sequences which is related to collectively compact operator sequences and operator upper-semi Fredholm sequences, and we prove that the collection of operator upper-semi Fredholm sequences with finite ascent（descent） is closed under commuting operator sequences perturbation class associated with them according to the thought of homotopy, which is a generalization of the results under semi-Fredholm operator conditions.

关 键 词：升标 降标 算子紧序列 算子上半Fredholm序列 一致降标 

分 类 号：O177.2[理学—数学]