关键词: open manifolds, Ricci curvature, conjugate radius, critical point, Excess func- tion, triangle comparison theorems

Abstract: In this paper,we study the relation between the excess of open manifolds and their topology by using the methods of comparison geometry.We prove that a complete open Riemmannian manifold with Ricci curvature negatively lower bounded is of finite topological type provided that the conjugate radius is bounded from below by a positive constant and its Excess is bounded by some function of its conjugate radius,which improves some results in [4].

Key words: open manifolds, Ricci curvature, conjugate radius, critical point, Excess func- tion, triangle comparison theorems