3-DIMENSIONAL LORENTZIAN MANIFOLDS WITH CONSTANT PRINCIPAL RICCI CURVATURES RHO(1)=RHO(2)NOT-EQUAL-RHO(3)

The aim of this paper is the study of (nonhomogeneous) three-dimension al Lorentzian manifolds whose Ricci curvature tensor is diagonalizable with two distinct constant eigenvalues. Two mistakes in a recent pape r by D. McManus [J. Math. Phys. 36, 362-369 (1995)] are pointed out an d corrected, and a complete (local) classification of the nonhomogeneo us manifolds of this type is given, thereby generalizing some results of O. Kowalski [Nagoya Math. J. 132, 1-36 (1993)] to the framework of Lorentzian geometry. (C) 1997 American Institute of Physics.