A note on the null surface formulation of GR

The purpose of this work is to study the structure and nature of the singul arities of wavefronts in flat space-time. We computed the behavior at the s ingularities of important objects that take place in the null surface formu lation of general relativity. As a secondary result we show that the Minkow ski space-time with non-trivial null surfaces is a solution of the null sur face approach to general relativity.