The method of lower and upper solutions for 2n2nth-order multi-point boundary value problems

In this paper, we consider the following 2nnth-order multi-point boundary value problems (−1)nu(2n)(t)=f(t,u(t),−u″(t),…,(−1)iu(2i)(t),…,(−1)n−1u(2n−2)(t)),0