Regular systems of differential-algebraic equations
We consider linear and nonlinear systems of differential-algebraic equ- ations. The conditions of reducibility and regularity of linear systems are obtained. The theorems connecting these notions are proved. The theorem about stability of nonlinear systems in the first approximation is proved under the conditions of existence of some global structural form. An arbitrary high unsolvability index and variable ranks of Jacobi matrices describing a system are allowed