| and physics (Institute of Theoretical Physics) at the University of Cologne. |
| Fellow of the Studienstiftung des Deutschen Volkes. |
| University Complutense de Madrid, Mathematics Institute, Algebra Dept. (3 months) |
| in perturbative quantum field theory) under Prof. D. Kreimer (IHÉS and Boston University) and Prof. W. Nahm (Bonn University) |
| Fellow of the Ev. Studienwerk Villigst. |