1. Faculty of Computer Science, Dalhousie University, 6050 University Ave., PO BOX 15000, Halifax, NS, Canada B3H4R2. E-mail: love.kalra@dal.ca, {soto,eem}@cs.dal.ca
2. School of Engineering and Computer Science, Washington State University Vancouver, 14204 NE Salmon Creek Ave., Vancouver, WA 98686, USA. E-mail: x.zhao@wsu.edu