COSMOLOGICAL MODELS WITH A VARIABLE COSMOLOGICAL TERM AND BULK VISCOUS MODELS

Recently, flat variable-A cosmological models have been discussed by B erman. It is shown that these models are equivalent to Perfect fluid m odels with bulk viscosity which have been presented previously. The mo del of Berman, which is free of particle creation and which is claimed to solve the entropy problem, is shown to be the usual Einstein-de Si tter model. The nonflat variable-LAMBDA solutions are obtained and the ir relationship to bulk viscous solutions is elucidated. Exponentially expanding solutions are also derived. The question of the stability o f the models is briefly addressed.