| Résume | Given a singular filtration of a manifold, we use singular foliations to
define a pseudo-differential calculus. The operators in our calculus have
a well defined principal symbol. We distinguish a characteristic set of
representations of the associated (singular) grading, on which the
invertibility of the principal symbol depends (Rockland condition). We
then show that invertibility implies hypoellipticity, by constructing a
parametrix. This is joint work with Erik van Erp, Omar Mohsen and Robert
Yuncken. |
