Affiliation: | aIAAI et Laboratoire LIF, Centre de Mathématiques et Informatique, 39 rue Joliot-Curie, F-13453 Marseille Cedex 13, France bDepartment of Mathematics, POSTECH, Pohang, South Korea cDepartment of Mathematics, University of Scranton, Scranton, PA 18510, USA dCNRS-I3S, ESSI, Route des Colles, 06 903 Sophia Antipolis, France |