[1] Max Planck Inst Software Syst, Campus E1 5, D-66123 Saarbrucken, Germany
[2] Indian Inst Technol Delhi, Hauz Khas, New Delhi 110016, India
[3] Indian Inst Technol Kharagpur, Kharagpur 721302, India
[4] Washington Univ St Louis, Sch Law, One Brookings Dr, St Louis, MO 63130 USA
[5] Swiss Fed Inst Technol, IFW E 47 2, CH-8092 Zurich, Switzerland