1. INRIA Saclay -- Île-de-France & LSV, ENS Cachan, Orsay Cedex, France
2. The University of Hong Kong, Pokfulam Road, Hong Kong
3. Free University of Bozen-Bolzano & INRIA Saclay -- Île-de-France, Bolzano, Italy
4. Free University of Bozen-Bolzano, Bolzano, Italy
5. Institut Télécom; Télécom ParisTech; CNRS LTCI, Paris, France