2 Calcul de Weyl et déformations
Pseudodifferential operators are studied, from the viewpoint of local solvability and under the assumption that, micro-locally, the principal symbol factorizes as with elliptic, homogeneous of degree , and homogeneous of degree one, satisfying the following condition : there is a point in the characteristic variety and a complex number such that at and such that the restriction of to the bicharacteristic strip of vanishes of order at , changing sign there from minus to...