Optimization and related fields proceedings of the "G. Stampacchia International School of Mathematics" held at Erice, Sicily, September 17-30, 1984 / edited by R. Conti, E. De Giorgi, and F. Giannessi. - Conti, Roberto, 1923-; De Giorgi, Ennio; Giannessi, F. (Lecture notes in mathematics (Springer-Verlag) ;, 1986)