Affiliation: | 1.Faculté des Sciences et Techniques,XLIM-DMI UMR CNRS 7252,Limoges,France;2.Laboratoire LIP (CNRS, ENS Lyon, Inria, UCBL), CNRS,Université de Lyon,Lyon Cedex 07,France;3.Raymond and Beverly Sackler Faculty of Exact Sciences, School of Mathematical Sciences,Tel-Aviv University,Ramat-Aviv,Israel;4.Dipartimento di Informatica,Università di Pisa,Pisa,Italy |