Tadashi Imaizumi, School of Management & Information Sciences, Tama University, JapanAkinori Okada, Rikkyo University, JapanSadaaki Miyamoto, University of Tsukuba, JapanFumitake Sakaori, Department of Mathematics, Chuo University, JapanYoshiro Yamamoto, Department of Mathematics, Tokai University, JapanMaurizio Vichi, Department of Statistical Sciences, Sapienza University of Rome, Italy