Affiliation: | 1. Department of Mathematics, “Gheorghe Asachi” Technical University of Iasi, Bd. Carol I, no. 11, Iasi - 700506, Romania;2. Faculty of Mathematics, “Alexandru Ioan Cuza” University of Iasi, Bd. Carol I, no. 9, and “Octav Mayer” Mathematics Institute of the Romanian Academy, Bd. Carol I, no. 8, Iasi - 700506, Romania |