The existence of solutions and positive solution of a first - order differential system with initial and multi-point boundary conditions

In this paper, we consider a nonlinear differential system with initial and multi - point boundary conditions. The existence of solutions is proved by using the Banach contraction principle or the Krasnoselskii?s fixed point theorem. Furthermore, the existence of positive solutions is also obtained by applying the Guo-Krasnoselskii?s fixed point theorem in cones. As a consequence of the Guo-Krasnosellskii?s fixed point theorem, the multiplicity of positive solutions is established.