  We consider the conformal Einstein equations for polytropic perfect fluid
cosmologies which admit an isotropic singularity. For the polytropic index
gamma strictly greater than 1 and less than or equal to 2 it is shown that the
Cauchy problem for these equations is well-posed, that is to say that solutions
exist, are unique and depend smoothly on the data, with data consisting of
simply the 3-metric of the singularity. The analogous result for gamma=1 (dust)
is obtained when Bianchi type symmetry is assumed.
