Unique continuation through transversal characteristic hypersurfaces
  We prove a unique continuation result for an ill-posed characteristic problem. A model problem of this type occurs in A.D.~Ionescu \& S.~Klainerman article (Theorem 1.1 in \cite{MR2470908}) and we extend their model-result using only geometric assumptions. The main tools are Carleman estimates and H\"ormander's pseudo-convexity conditions. 
Nicolas Lerner
math.AP