We show that the phase transition previously observed in dynamical triangulation models of quantum gravity can be understood as being due to the creation of a singular link. The transition between singular and non-singular geometries as the gravitational coupling is varied appears to be first order.
@article{arxiv.hep-lat/9709007,
title = {Singular Structure in 4D Simplicial Gravity},
author = {S. Catterall and R. Renken and J. Kogut},
journal= {arXiv preprint arXiv:hep-lat/9709007},
year = {2009}
}