Affiliation: | 1. Institut für Analysis, Leibniz Universität, Welfengarten 1, 30167 Hannover, Germany;2. Department of Mathematics, Faculty of Science and Technology, Science University of Tokyo, 2641 Yamazaki, Noda, Chiba (278-8510), Japan;3. Department of Mathematics, University of Hyogo, 2167 Shosha Himeji, Hyogo (671-2201), Japan |