Note on Goedel-type space-times

The Goedel-type space-times are examined under different conditions on the algebraic structure of the energy-momentum tensor. A generalization of the Bampi--Zordan theorem on Goedel-type models is given. Chakraborty's results are recast as a special case of the generalized Bampi--Zordan theorem. The Reboucas--Tiomno solution is shown to be the unique Goedel-type metric with an algebraic structure of the tachyon fluid type