Affiliation: | 1.Department of Mathematics and Computer Science, University of Cologne, Weyertal 86-90, 50931, Cologne, Germany ;2.Johann Radon Institute for Computational and Applied Mathematics, Austrian Academy of Science, Altenbergerstrasse 69, 4040, Linz, Austria ;3.Faculty of Science, Department of Computer Science, University of Bath, Bath, BA2 7AY, UK ; |