Symmetry of ground states of p-Laplace equations via the moving plane method

In this paper we use the moving plane method to get the radial symmetry about a point x(0) is an element of R-N Of the positive ground state solutions of the equation -div (/Du/(p-2)Du) = f(u) in R-N, in the case 1 < p < 2. Sire assume f to be locally Lipschitz continuous in (0, +infinity) and nonincreasing near zero but we do not require any hypothesis on the critical set of the solution. To apply the moving plane method we first prove a weak comparison theorem for solutions of differential inequalities in unbounded domains.