Affiliation: | 1. Department of Mathematics, Sogang University, Seoul, Republic of Korea;2. Department of Mathematical Sciences, KAIST, Daejeon, Republic of Korea;1. Faculty of Mathematics and Computer Science, Babe?-Bolyai University, 400084 Cluj-Napoca, str. M. Kog?lniceanu, nr. 1, Romania;2. Eötvös Loránd University, Faculty of Informatics, H-1117 Budapest, Pázmány P. sny 1/C, Hungary |