Affiliation: | (1) Department of Mathematics, McMaster University, L8S 4K1 Hamilton, Ontario, Canada;(2) Department of Mathematics, Kansas State University, 66506 Manhattan, KS, USA;(3) Department of Mathematics, McMaster University, L8S 4K1 Hamilton, Ontario, Canada;(4) Department of Mathematics, Brandon University, R7A 6A9 Brandon, Manitoba, Canada |