Analytic Hypoellipticity at Non-symplectic Poisson-treves Strata for Sums of Squares of Vector Fields
نویسندگان
چکیده
We consider an operator P which is a sum of squares of vector fields with analytic coefficients. The operator has a nonsymplectic characteristic manifold, but the rank of the symplectic form σ is not constant on CharP . Moreover the Hamilton foliation of the non symplectic stratum of the Poisson-Treves stratification for P consists of closed curves in a ring-shaped open set around the origin. We prove that then P is analytic hypoelliptic on that open set. And we note explicitly that the local Gevrey hypoellipticity for P is G and that this is sharp.
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