The phase space view of f(R) gravity

We study the geometry of the phase space of spatially flat Friedmann-Lemaitre-Robertson-Walker models in f® gravity, for a general form of the function f®. The equilibrium points (de Sitter spaces) and their stability are discussed, and a comparison is made with the phase space of the equivalent scalar-tensor theory. New effective Lagrangians and Hamiltonians are also presented.