Affiliation: | A1 Department of Computing and Electrical Engineering, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, UK E-mail: fairouz@cee.hw.ac.uk, A2 Department of Computer Science, University of Buenos Aires, Pabellón I - Ciudad Universitaria (1428) Buenos Aires, Argentina E-mail: rios@dc.uba.ar |