On the Ricci operator of locally homogeneous Lorentzian 3-manifolds
Lorentzian 3-manifolds split into four possible Segre types. In the paper the possible Segre types together with the possible eigenvalues of the Ricci tensor are determined for locally homogeneous (or curvature-homogeneous) Lorentzian 3-manifolds. BY previous work of the first author, the problem can be reduced to the case of a locally symmetric space or a 3-dimensional Lie group with a left invariant Lorentzian metric.
scientific article; zbMATH DE number 5624218