1. Institut de Recherche Mathématique Avancée, Université de Strasbourg, France; and the Erwin Schrödinger International Institute for Mathematical Physics, Vienna, Austria
2. Center for the Topology and Quantization of Moduli Spaces and Dept. of Math., Aarhus Univ., Aarhus, Denmark; Depts. of Math. and Physics, Caltech, Pasadena, Calif., USA; and the Erwin Schrödinger Int’l Institute for Mathematical Physics, Vienna, Austria