Four-dimensional curvature homogeneous spaces
Kouei Sekigawa, Hiroshi Suga, Lieven Vanhecke (1992)
Commentationes Mathematicae Universitatis Carolinae
Similarity:
We prove that a four-dimensional, connected, simply connected and complete Riemannian manifold which is curvature homogeneous up to order two is a homogeneous Riemannian space.