BTZ Black Hole Entropy from Ponzano-Regge Gravity
  The entropy of the BTZ black hole is computed in the Ponzano-Regge formulation of three-dimensional lattice gravity. It is seen that the correct semi-classical behaviour of entropy is reproduced by states that correspond to all possible triangulations of the Euclidean black hole. 
V.Suneeta, R.K.Kaul and T.R.Govindarajan