Space--time homogeneous models with torsion

A space-time homogeneous model is one in which the metric and the connection are invariant under a four-dimensional transitive Lie group. The Einstein-Cartan theory describes the effect of spin on geometry. The field equations require a stress-energy tensor and a spin tensor for a perfect fluid, and we give the required forms here. The main part of this paper is a presentation of several classes of space-time homogeneous solutions of the Einstein-Cartan equations for perfect fluid cosmological models