2006
- Prof. Dr. F. Brackx, Clifford Research Group, Ghent University, 8.02.06–11.02.06
- Prof. Dr. Hermann G. Matthies, TU Braunschweig, 2.02.06
2005
- Prof. Dr. Mathias Ehrgott, Department of Engineering Science, University of Auckland, New Zealand, 7.12.05.–9.12.05
- Dr. Radu-Alexandru Todor, ETH Zürich, 1.11.05–31.01.06
- Prof. Dr. Teresa Reginska, Institute of Mathematics, Polish Academy of Sciences, Warsaw, 1.11.05–30.11.05