  We study the quantum evolution of the early universe, its semi-classical
analogue together with inflationary regime, in view of a generalized modified
theory of gravity. The action is built by supplementing the non-minimally
coupled scalar-tensor theory of gravity with scalar curvature squared term and
a Gauss-Bonnet-dilatonic coupled term. It is generalized, since all the
parameters are treated as arbitrary functions of the scalar field. It is
interesting to explore the fact that instead of considering additional flow
parameters, an effective potential serves the purpose of finding inflationary
parameters. The dilaton stabilization issue appears here as a problem with
reheating. Addition of a cosmological constant term alleviates the problem, and
inflation is effectively driven by the vacuum energy density. Thus Gauss-Bonnet
term might play a significant role in describing late-time cosmic evolution.
