Article
Keywords:
differential equations of second order; two-point boundary value problems
Summary:
If $Y$  is a subset of the space  $\mathbb{R}^{n}\times {\mathbb{R}^{n}}$, we call a pair of continuous functions  $U$, $V$ $Y$-compatible, if they map the space $\mathbb{R}^{n}$ into itself and satisfy $Ux\cdot Vy\ge 0$, for all $(x,y)\in Y$ with $x\cdot y\ge {0}$. (Dot denotes inner product.) In this paper a nonlinear two point boundary value problem for a second order ordinary differential $n$-dimensional system is investigated, provided the boundary conditions are given via a pair of compatible mappings. By using a truncation of the initial equation and restrictions of its domain, Brouwer’s fixed point theorem is applied to the composition of the consequent mapping with some projections and a one-parameter family of fixed points  $P_{\delta }$ is obtained. Then passing to the limits as  $\delta $ tends to zero the so-obtained accumulation points are solutions of the problem.
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