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 " + 2ku' + lambdau. (C) 2001 Elsevier Science Inc, All rights reserved.
Cabada, A., Habets, P., & Lois, S. (2001). Monotone method for the Neumann problem with lower and upper solutions in the reverse order. Applied Mathematics and Computation, 117(1), 1-14. https://doi.org/10.1016/S0096-3003(99)00149-6 (Original work published 2001)