1. Departamento Engenharia Informatica, Universidade de Coimbra, Polo II, Coimbra, 3030, Portugal
2. Laboratoire de Recherche en Informatique, INRIA Futurs, Parc Club Orsay Universite, Orsay, 91893, France
3. School of Computer Science, Cardiff University, Queen's Buildings, Cardiff, CF24 3AA, United Kingdom