Papers, discussions and results of an advanced training course of the Land of Baden-Wuerttemberg at the Mathematical Research Institute Oberwolfach/Walke, 2-6 Dec 1985SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman