Affiliation: | a Faculty of Economics and Business Administration, the University of Kitakyushu, 4-2-1 Kitagata, Kokuraminami, Kitakyushu 802-8577, Japan;b Department of Applied Mathematics and Computer Science, Ghent University, Fuzziness and Uncertainty Modelling, Krijgslaan 281 (S9), B-9000, Gent, Belgium |