Elliptic singularities, θ-puzzle and domain walls

We study N=1 four-dimensional gluodynamics in the context of M-theory compactifications on elliptically fibered Calabi-Yau fourfolds. Gaugino condensates, θ-dependence, Witten index and domain walls are considered for singularities of type An-1 and Dn+4. It is shown how the topology of intersections among the irreducible components defining the singular elliptic fiber, determine the entanglement of vacua and the appearance of domain walls. (orig.)