Affiliation: | 1. Department of Mathematics , University of Manitoba , Winnipeg, MB, R3T 2N2, Canada E-mail: aku@cc.umanitoba.ca.;2. Department of Mathematics , University of Manitoba , Winnipeg, MB, R3T 2N2, Canada E-mail: jwiliam@cc.umanitoba.ca;3. Department of Mathematics , University of Manitoba , Winnipeg, MB, R3T 2N2, Canada E-mail: ye@cc.umanitoba.ca.;4. Nortel Networks , Nepean, Ontario E-mail: cji@nortelnetworks.com. |