## Non-embeddability of general unipotent diffeomorphisms up to formal conjugacy

Ribón, Javier
##### Description
The formal class of a germ of diffeomorphism $\phi$ is embeddable in a flow if $\phi$ is formally conjugated to the exponential of a germ of vector field. We prove that there are complex analytic unipotent germs of diffeomorphisms at $({\mathbb C}^{n},0)$ ($n>1$) whose formal class is non-embeddable. The examples are inside a family in which the non-embeddability is of geometrical type. The proof relies on the properties of some linear functional operators that we obtain through the study of polynomial families of diffeomorphisms via potential theory.
Comment: 20 pages, 1 figure To appear in Annales de l'Institut Fourier
##### Keywords
Mathematics - Dynamical Systems, Mathematics - Complex Variables, 37F75, 32H02, 32A05, 40A05