Institution: | 1. L.R.I, UMR 8623 CNRS-UPS, bât. 490, Université Paris-Sud, 91405 Orsay Cedex, France;2. School of Mathematics and Statistics, Lanzhou University, Lanzhou 730000, China;3. Department of Mathematics, East China Normal University, Shanghai 200062, China;1. Cracow,Poland;2. Cracow,Poland |