Lapse and shift in Regge calculus

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Abstract
I use my (3+1)-dimensional Regge calculus code to give the first explicit verification that there is an approximate diffeomorphism invariance in Regge calculus. In particular I evolve a neighborhood in a spacelike 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 Regge calculus, and find that they are proportional to the third power of the lattice spacing.