Enguica, RicardoSanchez, Luis2021-08-172021-08-172007-09-28Enguiça, R., & Sanchez, L. (2007). Existence and localization of solutions for fourth-order boundary-value problems. <i>Electronic Journal of Differential Equations, 2007</i>(127), pp. 1-10.1072-6691https://hdl.handle.net/10877/14341In this paper, we study the existence of solutions for the differential equation u(4)(t) = ƒ(t, u(t), u″(t)), where ƒ satisfies one-sided Lipschitz conditions with respect to u and u″, with periodic conditions or boundary conditions from "simply supported" beam theory. We assume the existence of lower and upper solutions (well-ordered and in some cases reversely ordered) and we make use of a fourth-order linear differential operator factorization.Text10 pages1 file (.pdf)enAttribution 4.0 InternationalBeam equationFourth order boundary value problemMaximum principlesLower and upper solutionsReversed orderArticle