Four-forms and the vanishing of the cosmological constant

We show that the dynamics (and statics) of a four-form are more subtle than previously appreciated, especially when used in conjunction with the Baum-Hawking-Coleman mechanism. We investigate the properties of the four-forms on closed euclidean, open euclidean, and lorentzian manifolds. We find that only under special conditions is their behaviour such that the cosmological constant vanishes. (orig.)