Institution: | (1) Department of Mathematics, Massey University, Private Bag 11222, Palmerston North, New Zealand;(2) Institut für Mathematik, Technische Universität Graz, Kopernikusgasse 24, A-8010 Graz, Austria;(3) Department of Combinatorics and Optimization, University of Waterloo, N2L 3G1 Waterloo, Ontario, Canada |