NSF 2.0: A spin weight zero formulation of General Relativity
  We present a set of three PDEs for three real scalars that are equivalent to the full Einstein equations without any symmetry assumptions. The main variables in this formulation are null surfaces and a conformal factor.   Furthermore, for asymptotically flat spacetimes the free data (representing gravitational radiation) enters as the source term in the resulting equations. This could be important for an asymptotic quantization procedure. 
Melina Bordcoch, Carlos Kozameh, Alejandra Rojas
gr-qc