Accelerating cosmologies from non-local higher-derivative gravity

We study accelerating cosmological solutions of a general class of non-linear gravities which depend on Gauss–Bonnet and other higher derivative invariants. To achieve this goal a local formulation with auxiliary scalars for arbitrary higher-derivative non-local gravity is developed. It is demonstrated that non-local Gauss–Bonnet gravity can be reduced, in the local formulation, to a model of string-inspired scalar-Gauss–Bonnet gravity. A natural unification, in the theory here developed, of the early-time inflation epoch with a late-time acceleration stage can also be realized.