Vienna, Austria.
Institute of Mathematics "Simion Stoilow" of the Romanian Academy.
Mathematics and computer science division.
Institut des Hautes Etudes Scientifiques, Bures-sur-Yvette, France.
Institut de Recherche Mathématique Avancée, Strasbourg, France.
Royal Swedish Academy of Sciences, Stockholm, Sweden.
Scuola Normale Superiore, Pisa, Italy
Max-Planck-Institute for mathematics in the sciences, Leipzig.