QUELQUES PROBLÈMES DE CAUCHY POUR LES ÉQUATIONS DIFFÉRENTIELLES NON-LINÉAIRES

Abstract

In this memory,we focus on the existence of solution for a nonlinear boundary problem of third and fourth differential equations using the method of upper and lower solutions and some fixed point theorems like Larey Schauder theorem and Guo-Krasnosel’skii and expansion of cones. .