EINSTEINS EQUATIONS IN THE PRESENCE OF SIGNATURE CHANGE

We discuss Einstein's field equations in the presence of signature cha nge using variational methods, obtaining a generalization of the Lancz os equation relating the distributional term in the stress tensor to t he discontinuity of the extrinsic curvature. In particular, there is n o distributional term in the stress tensor, and hence no surface layer , precisely when the extrinsic curvature is continuous, in agreement w ith the standard result for constant signature. (C) 1996 American Inst itute of Physics.