Some FRW models with variable G and Lambda

Einstein's field equations with G and Lambda both varying with time are considered in the context of general homogeneous, isotropic universes in a way which conserves the energy momentum tensor of the matter content. It is found that the solutions of the field equations, which are based on the variation of Lambda as R-2 but with different constants of proportionality, describe significantly different cosmological scenarios. It is also found that the non-static models with constant density having a vacuum-like equation of state are endowed with inflation for a wide class of functions G(t) and Lambda(t) and a static universe with constant density without the vacuum-like equation of state, can exist only for k = 1 with constant G and Lambda.