We discuss the interplay between standard canonical analysis and canonical
discretization in three-dimensional gravity with cosmological constant. By
using the Hamiltonian analysis, we find that the continuum local symmetries of
the theory are given by the on-shell space-time diffeomorphisms, which at the
action level, corresponds to the Kalb-Ramond transformations. At the time of
discretization, although this symmetry is explicitly broken, we prove that the
theory still preserves certain gauge freedom generated by a constant curvature
relation in terms of holonomies and the Gauss's law in the lattice approach.Comment: 19 pages, 1 figure. arXiv admin note: text overlap with
arXiv:1310.3759, arXiv:gr-qc/0512065, arXiv:1111.1879 by other author