UDC 517.9We establish necessary and sufficient conditions for the existence of solutions and propose an iterative scheme for the determination of solutions of the Fredholm weakly nonlinear boundary-value problem for a system of ordinary differential equations in the case of multiple roots of the equation for generating constants.
Statement of the ProblemWe study the problem of construction of the solution z.t; "/ W z.;We seek the solution of problem (1) in a small neighborhood of the solution of the generating problemHere, A.t/ is an .n n/ matrix and f .t / is an n -dimensional column vector whose elements are real functions continuous on the segment OEa; b and`z./ is a linear bounded vector functional`z./ W C OEa; b ! R m : Assume that the nonlinearities Z.z; t; "/ and J.z.; "/; "/ of the Fredholm .m ¤ n/ problem (1) are twice continuously differentiable with respect to the unknown z in a small neighborhood of the generating solution and with respect to the small parameter " in a small positive neighborhood of zero. In addition, we also assume that the vector function Z.z; t; "/ is continuous in the independent variable t on the segment OEa; b: We investigate the critical case .P Q 6 D 0/ under the assumption thatIn this case, the generating problem has an .r D n n 1 / -parameter family of solutionsHere, X.t/ is a normal .X.a/ D I n / fundamental matrix of the homogeneous part of the generating system, Q D`X./ is an .m n/ matrix, rank Q D n 1 ; X r .t / D X.t /P Q r ; P Q r is an .n r/ matrix formed by r