Monge-Ampere Functions, II Joseph Fu Indiana University Mathematics Journal 1989 text pdf 10.1512/iumj.1989.38.38036 10.1512/iumj.1989.38.38036 en Indiana Univ. Math. J. 38 (1989) 773 - 789 state-of-the-art mathematics http://iumj.org/access/