Eleven dimensional supergravity as a constrained topological field   theory
  We describe a new first-order formulation of D=11 supergravity which shows that that theory can be understood to arise from a certain topological field theory by the imposition of a set of local constraints on the fields, plus a lagrange multiplier term. The topological field theory is of interest as the algebra of its constraints realizes the D=11 supersymmetry algebra with central charges. 
Yi Ling and Lee Smolin