As I had studied quite a bit at University of Tokyo graduate school, I was able to complete my required courses during my first year at University of Minnesota in good order. This allowed me to look forward to summer vacation of 1965 with a sense of freedom. I had some unexpected good fortune that summer. Professor Hirofumi Uzawa at University of Chicago allowed me to join a workshop that he held for several outstanding graduate students from Massachusetts Institute of Technology (MIT). At that time Professor Uzawa was conducting joint research with Professor Hurwicz on the difficult problem of mathematically deriving demand function from utility function. He visited Minnesota occasionally to work on this joint project.