Remarks on iteration of formal automorphisms.
The intrinsic differential Galois group is a twisted form of the standard differential Galois group, defined over the base differential field. We exhibit several constraints for the inverse problem of differential Galois theory to have a solution in this intrinsic setting, and show by explicit computations that they are sufficient in a (very) special situation.
We give combinatorial models for non-spherical, generic, smooth, complex representations of the group , where is a non-Archimedean locally compact field. More precisely we carry on studying the graphs defined in a previous work. We show that such representations may be obtained as quotients of the cohomology of a graph , for a suitable integer , or equivalently as subspaces of the space of discrete harmonic cochains on such a graph. Moreover, for supercuspidal representations, these models...