3 citations · 4 across the 11 of their papers we have counts for
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Analytic hypoellipticity for on the Heisenberg group: an approach
David S. Tartakoff
In an interesting note, E.M. Stein observed some 20 years ago that while the Kohn Laplacian on functions is neither locally solvable nor (analytic) hypoelliptic, the ad…
A Class of Sums of Squares with a Given Poisson-Treves Stratification
Antonio Bove, David S. Tartakoff
We study a class of sum of squares exhibiting the same Poisson-Treves stratification as the Oleinik-Radkevič operator. We find three types of operators having distinct microlocal s…
An elementary proof of Fedi\uı's theorem and extensions
David S. Tartakoff
We present an elementary, proof of Fedi\uı's theorem on arbitrary (e.g., infinite order) degeneracy and extensions. In particular, the proof allows and shows Gev…
Analytic Hypoellipticity at Non-Symplectic Poisson-Treves Strata for Sums of Squares of Vector Fields
Antonio Bove, David S. Tartakoff
We consider an operator which is a sum of squares of vector fields with analytic coefficients. The operator has a non-symplectic characteristic manifold, but the rank of the…
Analytic Hypoellipticity in the Presence of Lower Order Terms
Paolo Albano, Antonio Bove, David S. Tartakoff
We consider a second order operator with analytic coefficients whose principal symbol vanishes exactly to order two on a symplectic real analytic manifold. We assume that the first…
Hypoellipticity and loss of derivatives with Appendix Analyticity and loss of derivatives
Joseph J. Kohn, Makhlouf Derridj, David S. Tartakoff
For each value of k, two complex vector fields satisfying the bracket condition are exhibited the sum of whose squares is hypoelliptic but not subelliptic - in fact the operator lo…