LFA is still a recommended tool for the analysis of discrete nonlinear operators like (5.1). To this end, the first step is to neglect boundary conditions and to extend the discrete operator to an infinite grid; the second step assumes that any discrete nonlinear operator can be linearized locally (by freezing coefficients) and can be replaced locally by an operator with constant coefficients [47]. This method has been successfully applied to obtain a bet- ter understanding of MG algorithms applied to nonlinear problems or linear problems with discontinuous coefficients [1, 34, 15, 10, 4].