Existenz und erste Einschließung positiver Lösungen bei superlinearen Randwertaufgaben zweiter Ordnung

Summary Some classes of second-order superlinear boundary value problems are considered. Using M. A. Krasnoselskii's fixed point theorem for operators expanding a cone in a real Banach space we can prove new existence theorems for positive solutions for nonlinearities not necessarily satisfying a condition of Nagumo-type. At the same time, we give first bounds for the solutions.