We introduce a full approximation storage (FAS) multigrid algorithm to find
the finite element solution for a class of nonlinear monotone elliptic pro
blems. Since the solution of the problem is equivalent to minimize a strict
ly convex functional, we use a Polak-Ribiere conjugate gradient method as t
he nonlinear smoother in our algorithm. The advantage in so doing is that w
e do not have to calculate derivatives of operators. We prove local converg
ence of our algorithm and illustrate its performance by solving benchmark p
roblems.