Affiliation: | 1. Research Department, Faculty of Mathematics, ‘Alexandru Ioan Cuza’ University of Iasi, Bd. Carol I, no. 11, 700506 Iasi, Romania;2. Department of Mathematics and Informatics, ‘Gheorghe Asachi’ Technical University of Iasi, Bd. Carol I no. 11, 700506 Iasi, Romania. simona.romaniuc@tuiasi.ro;3. Department of Mathematical Sciences, Yamagata University, Yamagata, 990-8560, Japan;4. Institute of Mathematics, University of Tsukuba, 1-1-1 Tennodai Tsukuba, Ibaraki, 305-8571, Japan. inoguchi@math.tsukuba.ac.jp;5. Faculty of Mathematics, ‘Alexandru Ioan Cuza’ University of Iasi, Bd. Carol I, no. 11, 700506 Iasi, Romania. marian.ioan.munteanu@gmail.com;6. Faculty of Mathematics, ‘Alexandru Ioan Cuza’ University of Iasi, Bd. Carol I, no. 11, 700506 Iasi, Romania. marian.ioan.munteanu@gmail.com;7. Department of Mathematics and Informatics, ‘Gheorghe Asachi’ Technical University of Iasi, Bd. Carol I no. 11, 700506 Iasi, Romania. ana.irina.nistor@gmail.com |