Centralizers of locally nilpotent derivations

AbstractLocally nilpotent derivations of the polynomial ring in n variables over the complex field, algebraic actions of the additive group Ga of complex numbers on Cn, and vector fields on Cn admitting a strictly polynomial flow, are equivalent objects. The polynomial centralizer of the vector field corresponding to a triangulable locally nilpotent derivation is investigated, yielding a triangulability criterion. Several new examples of nontriangulable Ga actions on Cn are presented