Analysis of solvability for weak nonlinear differential algebraic systems

In this paper we consider the system of differential algebraic equations with a linear part and a small nonlinear term. We refer to such systems as weak nonlinear. Coefficient matrices of the linear part might be rectangular. Additionally, it is assumed that the solution meets some boundary conditions of a general kind. Basic assumption for the linear part is that it can be reduced to canonic form introduced by V.F. Chistyakov. By applying a special technique, analysis of the boundary problem is reduced to mastering of an operator which becomes a compression at a sufficiently small parameter. Under assumptions mentioned, we obtain sufficient and necessary existence conditions for weak nonlinear differential algebraic systems.