Dynamical system methods are used in the study of the stability of spatially
flat homogeneous cosmologies within a large class of generalized modified
gravity models in the presence of a relativistic matter-radiation fluid. The
present approach can be considered as the generalization of previous works in
which only F(R) cases were considered. Models described by an arbitrary
function of all possible geometric invariants are investigated and general
equations giving all critical points are derived.Comment: 13 pages, no figure