N. NYAMORADI - Department of Mathematics, Faculty of Sciences, Razi University, ۶۷۱۴۹ Kermanshah, Iran.

In this work, by employing the Krasnosel skii fixed point theorem, we study the existence of positive solutions of a three-point boundary value problem for the following fourth-order differential equation begin{eqnarray*} left { begin{array}{ll} u^{(4)}(t) -f(t,u(t),u^{prime prime }(t))=0 hspace{1cm} 0 leq t leq 1, & u(0) = u(1)=0, hspace{1cm} alpha u^{prime prime }(0) - beta u^{prime prime prime }(0)=0, hspace{1cm} u^{prime prime }(1)- alpha u^{prime prime }(eta)=0, & end{array} right. end{eqnarray*} where $beta > 0, 0< eta 0$.

Positive solution, Fourth-order boundary value problem, Three-point boundary conditions, fixed point theorem