This paper presents a
technique for establishing the existence of conjugate points for real fourth
order differential equations defined on an interval [α,∞). The point β > α is
conjugate to α if there exists a nontrivial solution y(x) of the equation which
satisfies
An important feature of this technique is that it is not limited to equations of
selfadjoint type and that the general theory applies to nonlinear equations as
well.