Institution: | (1) Department of Mathematics, Harvard University, 02138 Cambridge, MA, USA;(2) Mathematisches Institut, Universität Münster, D-4400 Münster, Federal Republic of Germany;(3) Max-Planck-Institut für Mathematik, Gottfried-Claren-Strasse 26, D-5300 Bonn, Federal Republic of Germany;(4) Department of Mathematics, University of Maryland, 20742 College Park, MD, USA |