Un invariant algébrique associé à une application continue
Une caractérisation du fibré transverse.
We prove that the Lie algebra of infinitesimal automorphisms of the transverse structure on the total space of the transverse bundle of a foliation is isomorphic to the semi-direct product of the Lie algebra of the infinitesimal automorphism of the foliation by the vector space of the transverse vector fields. The derivations of this algebra are entirely determined and we prove that this Lie algebra characterises the foliated structure of a compact Hausdorff foliation.
Universal prolongation of linear partial differential equations on filtered manifolds
The aim of this article is to show that systems of linear partial differential equations on filtered manifolds, which are of weighted finite type, can be canonically rewritten as first order systems of a certain type. This leads immediately to obstructions to the existence of solutions. Moreover, we will deduce that the solution space of such equations is always finite dimensional.