Description

Maximally subelliptic partial differential equations (PDE) are a far-reaching generalization of elliptic PDE. Elliptic PDE hold a special place: sharp results are known for general linear and fully nonlinear elliptic PDE. Over the past half-century, important results for elliptic PDE have been generalized to maximally subelliptic PDE. This text offers a presentation of these results and establishes the sharp regularity theory.