Institution: | Department of Mathematics & Statistics, State University of New York, The University at Albany, Albany, New York 12222 ; Mathematisches Institut, Universität Erlangen--Nürnberg, Bismarckstr. 1 1/2, D--91054 Erlangen, Germany ; Department of Mathematics, North Dakota State University, Fargo, North Dakota 58105 and Institute of Mathematics, Chinese Academy of Sciences, Beijing 100080, People's Republic of China |