Between 1977-1981 , he got his " maitrise " degree in mathematics from Paris Diderot University . Later , he made a doctorate on mathematical logic and algebra at Yale University in USA , and worked as a lecturer at University of California Berkeley Campus between 1985-1986 . He worked as an assistant professor at Notre Dame University between 1987 and 1989 , then as an associate professor at the University of California Irvine Campus until 1995 , and later as a professor .