THE ASCENT AND DESCENT OF OPERATOR SEQUENCES
LI Shao-kuan · Journal of Mathematics · 2009
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.