1. Department of Engineering and Computer Science, University of Trento, Italy. E-mails: colombo@disi.unitn.it, palopoli@disi.unitn.it
2. Department of Industrial Engineering, University of Trento, Italy. E-mail: daniele.fontanelli@unitn.it
3. INRIA Rennes – Bretagne Atlantique, France. E-mails: axel.legay@inria.fr, sean.sedwards@inria.fr