Singular Vertices in the Strong Coupling Phase of Four-Dimensional Simplicial Gravity

We study four-dimensional simplicial gravity through numerical simulationwith special attention to the existence of singular vertices, in the strongcoupling phase, that are shared by abnormally large numbers of four-simplices. We attempt to cure this disease by adding a term to the action whichsuppresses such singular vertices. For a sufficiently large coefficient of theadditional term, however, the phase transition disappears and the system isobserved to be always in the branched polymer phase for any gravitationalconstant.Comment: 11 pages, 7 Postscript figure