Monotone method for the Neumann problem with lower and upper solutions in the reverse order

摘要

This work is devoted to the study of the existence and approximation of solutions of the problem u″=f(t,u,u′),u′(a)=u′(b)=0 in the presence of lower and upper solutions in the reverse order. To this end we prove anti-maximum principles for the nonlinear operator u″+2k|u′|+λu.