Ueber das Spektrum des Laplace-Operators auf kompakten Riemannschen Flächen.
Un principe de concentration-compacité pour les suites de surfaces Riemanniennes
Uniqueness of Harmonie Mappings and of Solutions of Elliptic Equations on Riemannnian Manifolds.
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.