Commun. Korean Math. Soc. 1998 Vol. 13, No. 1, 95-107
Myung-Jin Jeon Semyung University
Abstract : In this paper we prove the Hopf-Rinow theorem for CAT (0) spaces and show that the ideal boundaries of complete CAT(0) manifolds of dimension 2 or 3 with some additional conditions are homeomorphic to the circle or 2-sphere by the characterization of the local shadows around the branch points.
Keywords : CAT(0) space, ideal boundary, branch point, shadow