INRIA Rhône-Alpes, Inovallée, Montbonnot, Saint Ismier Cedex, France. Eric.Tannier@inria.fr|INRIA Rhône-Alpes, Inovallée, Montbonnot, Saint Ismier Cedex, France. Eric.Tannier@inria.fr|INRIA Rhône-Alpes, Inovallée, Montbonnot, Saint Ismier Cedex, France. Eric.Tannier@inria.fr