SPACE-TIMES ADMITTING A 3-DIMENSIONAL CONFORMAL-GROUP

Perfect fluid space-times admitting a three-dimensional Lie group of c onformal motions containing a two-dimensional Abelian Lie subgroup of isometries are studied. Demanding that the conformal Killing vector be proper (i.e., not homothetic nor Killing), all such space-times are c lassified according to the structure of their corresponding three-dime nsional conformal Lie group and the nature of their corresponding orbi ts (that are assumed to be non-null). Each metric is then explicitly d isplayed in coordinates adapted to the symmetry vectors. Attention is then restricted to the diagonal case, and exact perfect fluid solution s are obtained in both the cases in which the fluid four-velocity is t angential or orthogonal to the conformal orbits, as well as in the mor e general ''tilting'' case.