Positive solutions of a nonlinear three-point boundary-value problem.

We study the existence of positive solutions to the boundary-value problem u + a(t)f(u) = 0, t ∈ (0, 1) u(0) = 0, αu(η) = u(1) , where 0 < η < 1 and 0 < α < 1/η. We show the existence of at least one positive solution if f is either superlinear or sublinear by applying the fixed point theorem in cones.