A Large N expansion for Gravity
  A Large N expansion for gravity is proposed. The scheme is based on the splitting of the Einstein-Hilbert action into the BF topological action plus a constraint. The method also allows to include matter fields. The relation between matter and non orientable fat graphs in the expansion is stressed; the special role of scalars is shortly discussed. The connections with the Holographic Principle and higher spin fields are analyzed. 
F. Canfora