2 papers
math.CV2010
Loss of derivatives in the infinite type
T. V. Khanh, S. Pinton, G. Zampieri
We discuss loss of derivatives for degenerate vector fields obtained from infinite type exponentially non-degenerate hypersurfaces of $\C^2$.
math.CV2010
Loss of derivatives for systems of complex vector fields and sums of squares
Tran Vu Khanh, Stefano Pinton, Giuseppe Zampieri
We discuss, both for systems of complex vector fields and for sums of squares, the phenomenon discovered by Kohn of hypoellipticity with loss of derivatives.