Let F = F(nu(1),..., nu(m)) smooth on (R-0(+))(m) with F-nu i nu j greater
than or equal to 0 for i not equal j. Furthermore, let u(1),..., u(m) nonne
gative and bounded functions on R-n with compact support. We prove the ineq
uality integral(Rn) F(u(1),...,u(m))dx less than or equal to integral(Rn) F
(u(1)*,..., u(m)*) dx, where * denotes symmetric decreasing rearrangement.