Link of groups and homogeneous Hörmander operators
Alessia Elisabetta Kogoj, Ermanno Lanconelli · Proceedings of the American Mathematical Society · 2007
We study a notion of link of Lie groups suggested by the structure of the partial differential operators of Kolmogorov type. As an application of our link procedure we construct explicit examples of stratified Lie groups, with dimension and step arbitrarily large. We also give a set of examples of hypoelliptic second-order operators which are left translation invariant and homogeneous of degree two on the previous groups.