Institution: | 1. Mathematical Sciences , Osaka Kyoiku University , Kashiwara, Osaka 582-8582, Japan ashino@cc.osaka-kyoiku.ac.jp;3. Research Center for Physics and Mathematics , Osaka Electro-Communication University , Neyagawa, Osaka 572-8530, Japan;4. Information Science , Osaka Kyoiku University , Kashiwara, Osaka 582-8582, Japan |