Affiliation: | 1. Department of Mathematics, University of Scranton, Scranton, PA 18510, USA;2. University of Chester, Department of Mathematics, Chester, UK;3. Sampoerna Academy, L''Avenue Campus, 12780, Jakarta, Indonesia;4. Department of Algebra, Uzhgorod State University, Uzhgorod, Ukraine;5. Department of Mathematics & Statistics, Northern Arizona University, Flagstaff, AZ 86001, USA |