Global analytic hypoellipticity for a class of quasilinear sums of squares of vector fields

Abstract

A global real analytic regularity theorem for a quasilinear sum of squares of vector fields of Hormander rank 2 is given. A related local result for a special case was proved recently by the second author and L. Zanghirati in a paper titled Local Real Analyticity of Solutions for sums of squares of non-linear vector fields.