Complete Homogeneous Riemannian Manifolds of Negative Sectional Curvature.
We study conformally flat Lorentzian three-manifolds which are either semi-symmetric or pseudo-symmetric. Their complete classification is obtained under hypotheses of local homogeneity and curvature homogeneity. Moreover, examples which are not curvature homogeneous are described.
We give the complete classification of conformally flat pseudo-symmetric spaces of constant type.
We obtain the complete classification of conformally flat semi-symmetric spaces.