Affiliation: | 1. Mathematics, Irving K. Barber School, University of British Columbia Okanagan, Kelowna, BC, Canada V1V 1V7;2. Department of Pure Mathematics, Center of Excellence in Analysis on Algebraic Structures (CEAAS), Ferdowsi University of Mashhad, Iran;3. Department of Mathematics, Shanghai University, Shanghai 200444, China;4. School of Fundamental Studies, Shanghai University of Engineering Science, Shanghai 201620, China |