Affiliation: | 1. Department of Mathematics and Applications R. Caccioppoli, University of Naples Federico II, Via Claudio, 80125 Naples, Italy;2. Department of Economics and Statistics & CSEF, University of Naples Federico II, Via Cinthia, 80126 Naples, Italy;1. Department of Liberal Arts, National Institute of Technology, Toyama College, Toyama 939-8630, Japan;2. Department of Mathematics, Waseda University, Tokyo 169-8555, Japan |