Affiliation: | 1.Department of Mathematics, National Technical University, Zografou Campus, 15780, Athens, Greece ;2.Faculty of Applied Mathematics, AGH University of Science and Technology, 30-059, Krakow, Poland ;3.Department of Mathematics, University of Craiova, 200585, Craiova, Romania ;4.Faculty of Education and Faculty of Mathematics and Physics, University of Ljubljana, 1000, Ljubljana, Slovenia ;5.Institute of Mathematics, Physics and Mechanics, 1000, Ljubljana, Slovenia ; |