We derive four-dimensional gauge theories with the exceptional groups
F-4, E-8, E-7, and E-7 with matter, by starting from the duality betwe
en the heterotic string on K3 and F-theory on a elliptically fibered C
alabi-Yau 3-fold. This configuration is compactified to four dimension
s on a torus, and by employing toric geometry, we compute the type IIB
mirrors of the Calabi-Yaus of the type IIA string theory. We identify
the Seiberg-Witten curves describing the gauge theories as ALE spaces
fibered over a P-1 base. (C) 1997 Elsevier Science B.V.