Systems-conjugate and focal points of fourth order nonselfadjoint differential equations

Abstract

Systems-conjugate points have been studied by John Barrett in relation to selfadjoint fourth order differential equations of the form ( p 2 u ) + p 0 u = 0 ({p_2}u) + {p_0}u = 0 . This paper extends his results to the general nonselfadjoint fourth order differential equation via a system of second order equations.