Harnack inequality for a class of strongly degenerate elliptic operators formed by H?rmander vector fields

摘要

We prove Harnack inequality and regularity for solutions of a linear strongly degenerate elliptic equation. We assume the lower order terms in Stummel-Kato classes with respect to the Carnot-Carathéodory metric. We follow the pattern by Serrin in Acta Math 111:247-302, (1964).