LAPSE AND SHIFT IN REGGE CALCULUS

I use my (3 + 1)-dimensional Regge calculus code to give the first exp licit verification that there is an approximate diffeomorphism invaria nce in Regge calculus. In particular I evolve a neighborhood in a spac elike hypersurface numerically, and show that one may choose lapse and shift freely. I use my numerical approach to analyze the structure of this discrete diffeomorphism group. I also study the constraints in R egge calculus, and find that they are proportional to the third power of the lattice spacing.