Maximum principles for nonlinear elliptic equations in unseparated variables
Hailiang Zhang, Haina Xu · 2011
This paper is devoted to a class of nonlinear elliptic equations posed by Schaefer in 1977. We obtain maximum principles for certain functions, which are defined on solutions of the elliptic equations in unseparated variables form. The principles may be used to deduce some bounds on important quantities in physical problems of interest.