Simulating four-dimensional simplicial gravity using degenerate triangulations - art. no. 124008.

We extend a model of four-dimensional simplicial quantum gravity to include degenerate triangulations in addition to the combinatorial triangulations traditionally used. Relaxing the constraint that every 4-simplex is uniquel y defined by a set of live distinct vertices, we allow triangulations conta ining multiply connected simplexes and distinct simplexes defined by the sa me set of vertices. We demonstrate numerically that including degenerated t riangulations substantially reduces the finite-size effects in the model. I n particular, we provide strong numerical evidence for an exponential bound on the entropic growth of the ensemble of degenerate triangulations,and sh ow that a discontinuous crumpling transition is already observed on triangu lations of volume N-4 approximate to 4000. [S0556-2821(99)01812-3].