In the case of the Heisenberg group these are the contact mappings in the classical sense and they exist in abundance. In this paper it is shown that if the dimension of the center of N is at least three, then the generalized contact mappings are in the automorphism group of a finite dimensional Lie algebra g . The elements in g are the infinitesimal generators of local one parameter subgroups of generalized contact transformations.
Rigidity is defined as the property that g is finite dimensional.
This work has been supported by the Swiss National Science Foundation.