1. National Research University Higher School of Economics; Department of Mathematics; Laboratory of Algebraic Geometry; Vavilova 7 117332 Moscow Russia
2. Institut Elie Cartan; Université Henri Poincaré; B. P. 70239 F-54506 Vandoeuvre-lès-Nancy cedex France
3. Institut Universitaire de France
4. KIAS; Hoegiro 85 Seoul South Korea