Bianchi-type string cosmology

Bianchi-type string cosmology involves generalizations of the FRW backgrounds with three transitive spacelike Killing symmetries, but without any a priori assumption of isotropy in the 3D sections of homogeneity. With emphasis on diagonal-metric and vanishing cosmological constant cases which have not been previously examined in the literature, the present findings allow an overview and the classification of all Bianchi-type backgrounds. These string solutions (at least to lowest order in α′) offer prototypes for the study of spatial anisotropy and its impact on the dynamics of the early universe.