The Lagrangian of a Self-Dual Gravitational Field as a Limit of the SDYM   Lagrangian
  The action for the su(N) SDYM equations is shown to give in the limit $N \to \infty$ the action for the six-dimensional version of the second heavenly equation. The symmetry reductions of this latter equation to the well known equations of self-dual gravity are given. The Moyal deformation of the heavenly equations are also considered. 
Jerzy Plebanski and Maciej Przanowski