  We continue our study of geometric transitions in type II and heterotic
theories. In type IIB theory we discuss an F-theory setup which clarifies many
of our earlier assumptions and allows us to study gravity duals of N = 1 gauge
theories with arbitrary global symmetry group G. We also point out the subtle
differences between global and local metrics, and show that in many cases the
global descriptions are far more complicated than discussed earlier. We
determine the full global description in type I/heterotic theory.
  In type IIA, our analysis gives rise to a local non-Kahler metric whose
global description involves a particular orientifold action with gauge fluxes
localised on branes. We are also able to identify the three form fields that
allow for a smooth flop in the M-theory lift. We briefly discuss the issues of
generalised complex structures in type IIB theory and possible half-twisted
models in the heterotic duals of our type II models. In a companion paper we
will present details on the topological aspects of these models.

High Energy Physics - Theory