Fatima K. Abu Salem Associate Professor, DPhil Oxon Associate Professor, DPhil OxonComputer Science DepartmentAmerican University of BeirutP. O. Box 11-0236 Riad El SolhBeirut 1107 2020Lebanon e-mail: fatima.abusalem “at” aub.edu.lbĀ Tel.: +961-1-350000 ext. 4224 Fax: +961-1-744461