Yohji Akama
(1), Atina Husnaqilati
(2)
(1)
Department of Mathematics, Graduate School of Science, Tohoku University, Aramaki, Aoba, Sendai, 980-8578, Japan, Japan,
(2)
Department of Mathematics, Graduate School of Science, Tohoku University, Aramaki, Aoba, Sendai, 980-8578, Japan, Japan