  The modified F(R)-scalar-Gauss-Bonnet gravity is proposed as dark energy
model. The reconstruction program for such theory is developed. It is
explicitly demonstrated that the known classical universe expansion history
(deceleration epoch, transition to acceleration and effective quintessence,
phantom or cosmological constant era) may naturally occur in such unified
theory for some (reconstructed) classes of scalar potentials. Gauss-Bonnet
assisted dark energy is also proposed. The possibility of cosmic acceleration
is studied there.
