Department of Computing Science, University of Alberta, Edmonton, AB, T6G 2E8, Canada. montgomerie@shaw.ca|Department of Computing Science, University of Alberta, Edmonton, AB, T6G 2E8, Canada. montgomerie@shaw.ca|Department of Computing Science, University of Alberta, Edmonton, AB, T6G 2E8, Canada. montgomerie@shaw.ca|Department of Computing Science, University of Alberta, Edmonton, AB, T6G 2E8, Canada. montgomerie@shaw.ca