Affiliation: | (1) Department of Mathematical Science, Faculty of Engineering Science, Osaka University, 560 Toyonaka, Osaka, Japan;(2) Mathematisches Institut, Universitat Erlangen-Nürnberg, Bismarckstrasse 1 1/2, W-8520 Erlangen, Germany;(3) Department of Mathematics, Faculty of Science, Science Univesity of Tokyo, Wakamiya 26 Shinjuku, Tokyo, Japan |