image The following anecdote illustrates the level of the initial confusion. The first elaborate graphical computation of the eigenvalues of the area led to the mysterious formula image, with integer p . One day, Junichi Iwasaki, at the time a student, stormed into my office and told me to rewrite the formula in terms of the half integer image . This yields the very familiar expression for the eigenvalues of the SU (2) Casimir image . Nobody had previously noticed this fact.