A constructive generalised Goursat normal form

Abstract

We provide necessary and sufficient conditions on the derived type of a vector field distribution $\Cal V$ in order that it be locally equivalent to a partial prolongation of the contact distribution $\Cal C^{(1)}_q$, on the first order jet bundle of maps from $\mathbb{R}$ to ${\mathbb{R}}^q$, $q\ge 1$. This result fully generalises the classical Goursat normal form. Our proof is constructive: it is proven that if $\Cal V$ is locally equivalent to a partial prolongation of $\Cal C^{(1)}_q$ then the explicit construction of contact coordinates algorithmically depends upon the integration of a sequence of geometrically defined and algorithmically determined integrable Pfaffian systems on the ambient manifold.

33 pages