Computer Sciences Department, University of Cape Town, South Africa. gsalazar@cs.uct.ac.za|Computer Sciences Department, University of Cape Town, South Africa. gsalazar@cs.uct.ac.za|Computer Sciences Department, University of Cape Town, South Africa. gsalazar@cs.uct.ac.za|Computer Sciences Department, University of Cape Town, South Africa. gsalazar@cs.uct.ac.za|Computer Sciences Department, University of Cape Town, South Africa. gsalazar@cs.uct.ac.za|Computer Sciences Department, University of Cape Town, South Africa. gsalazar@cs.uct.ac.za