A pseudo-differential calculus on graded Lie groups
  In this paper, we present first results of our investigation regarding symbolic pseudo-differential calculi on nilpotent Lie groups. On any graded Lie group, we define classes of symbols using difference operators. The operators are obtained from these symbols via the natural quantisation given by the representation theory. They form an algebra of operators which shares many properties with the usual Hormander calculus. 
Veronique Fischer and Michael Ruzhansky
math.FA math.AP math.RT