IUMJ

Title: On the lifting and approximation theorem for nonsmooth vector fields

Authors: Marco Bramanti, Luca Brandolini and Marco Pedroni

Issue: Volume 59 (2010), Issue 6, 2093-2138

Abstract:

We prove a version of Rothschild-Stein's theorem of lifting and approximation and some related results in the context of nonsmooth Hoermander's vector fields for which the highest order commutators are only Hoelder continuous. The theory explicitly covers the case of one vector field having weight two while the others have weight one.