An Extension of H Ormander's Theorem for Infinitely Degenerate Second-order Operators
نویسنده
چکیده
We establish the hypoellipticity of a large class of highly degenerate second order di erential operators of H ormander type. The hypotheses of our theorem allow Hormander's general Lie algebra condition to fail on a collection of hypersurfaces. The proof of the theorem is probabilistic in nature. It is based on the Malliavin calculus and requires new sharp estimates for di usion processes in Euclidean space.
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