[1] PSL Res Univ, Univ Paris Dauphine, CEREMADE, CNRS,UMR 7534, F-75016 Paris, France
[2] Aalto Univ, Dept Math & Syst Anal, Espoo, Finland
[3] Ecole Normale Super Lyon, CNRS, UMPA, UMR 5669, Lyon, France
[4] Univ Bordeaux, CNRS, UMR 5251, IMB, Bordeaux, France