A definition of the Ponzano–Regge quantum gravity model in terms of surfacesa)

We show that the partition function of the Ponzano-Regge quantum gravity model can be written as a sum over surfaces in a $(2+1)$ dimensional space-time. We suggest a geometrical meaning, in terms of surfaces, for the (regulated) divergences that appear in the partition function.Comment: latex 14 pages (10 pages of text, 4 pages of figures), 4 epsfig figures, University of Pittsburgh preprint. No change has been made. The previous file has been corrupte