The Moduli space of Enriques surfaces and the fake monster lie superalgebra

We show that the moduli space of complex Enriques surfaces is an affine variety with a copy of the affine line removed. We do this by using the denominator function of a generalized Kac-Moody superalgebra (associated with superstrings on a 10-dimensional torus) to construct a non-vanishing section of an ample line bundle on the moduli space.