  We study solutions of the Wheeler-DeWitt equation corresponding to an
S-modular invariant N=1 supergravity model and a closed homogeneous and
isotropic Friedmann-Robertson-Walker spacetime. The issues of inflation and of
the cosmological constant problem are addressed with the help of the relevant
wave functions. We find that topological type inflation is consistent from the
quantum mechanical point of view and that a solution for the cosmological
constant problem along the lines of the strong CP problem naturally arises.
