On the geometry of Goursat structures
A Goursat structure on a manifold of dimension is a rank two distribution such that dim , for , where denote the elements of the derived flag of , defined by and . Goursat structures appeared first in the work of von Weber and Cartan, who have shown that on an open and dense subset they can be converted into the so-called Goursat normal form. Later, Goursat structures have been studied by Kumpera and Ruiz. In the paper, we introduce a new local invariant for Goursat structures, called...