Discrete Gravity Models and Loop Quantum Gravity: a Short Review
  We review the relation between Loop Quantum Gravity on a fixed graph and discrete models of gravity. We compare Regge and twisted geometries, and discuss discrete actions based on twisted geometries and on the discretization of the Plebanski action. We discuss the role of discrete geometries in the spin foam formalism, with particular attention to the definition of the simplicity constraints. 
Maite Dupuis, James P. Ryan and Simone Speziale
gr-qc