Area-preserving structure of 2d-gravity
  The effective action for 2d-gravity with manifest area-preserving invariance is obtained in the flat and in the general gravitational background. The cocyclic properties of the last action are proved, and generalizations on higher dimensions are discussed. 
D.R. Karakhanyan, R.P. Manvelyan, R.L. Mkrtchyan (Yerevan Physics   Institute)