1. Management Science and Business Economics Group, University of Edinburgh Business School, 29 Buccleuch Place, EH89JS Edinburgh, UK
2. Department of Mathematics and Systems Analysis, Aalto University, P.O. Box 11100, 00076 Aalto, Finland
3. Department of Electrical Engineering, Universidad de Castilla-La Mancha, Avenida Carlos III s/n, 45071 Toledo, Spain