  We prove the existence of a spectral resolution of the Wheeler-DeWitt
equation when the matter field is provided by a Yang-Mills field, with or
without mass term, if the spatial geometry of the underlying spacetime is
homothetic to $\R[3]$. The energy levels of the resulting quantum model, i.e.,
the eigenvalues of the corresponding self-adjoint Hamiltonian with a pure point
spectrum, are strictly positive.
