Cosmological evolution and exact solutions in a fourth-order theory of gravity

A fourth-order theory of gravity is considered which in terms of dynamics has the same degrees of freedom and number of constraints as those of scalar-tensor theories. In addition, it admits a canonical pointlike Lagrangian description. We study the critical points of the theory, and we show that it can describe the matter epoch of the Universe and that two accelerated phases can be recovered, one of which describes a de Sitter universe. Finally, for some models exact solutions are presented.