Affiliation: | (1) Department of Mathematical Sciences, Osaka Prefecture University, Sakai 599-8531, Japan;(2) Department of Mathematical and Statistical Methods, Agricultural University of Pozna, PL-60-637 Pozna, ul. Wojska Polskiego 28, Poland;(3) Department of Mathematics, Keio University, Yokohama 223-8522, Japan;(4) Department of Nursing, Gifu College of Nursing, Hashima 501-6295, Japan;(5) Present address: Graduate School of Information Science, Nagoya University, Nagoya 4648601, Japan |