Bachelor, Master in Tokyo University (Department of Information Science) Doctor course in Tokyo University (Department of Mathematics) Inturrupted to be employed as a research associate of RIMS, Kyoto Univ., in 1990 Oct. Ph.D at Kyoto University, 1995 Jan. Employed as a lecturer in Dept. of Math. in Keio University, 1995 Sept. Promoted to an associate professor in 1998 Apr. A visitting researcher in Max-Planck-Institute for Mathematics at Bonn, Apr.-Sept. 1997. An invited researcher in Nice University, Mar. 1998. An associate professor at Kyushu Univ. Dept. of Math., Apr. 1999. An associate professor at Kyoto Univ. Faculty of Integrated Human Studies, Apr. 2000. A professor at Hiroshima Univ. Dept. of Math., Apr. 2002.