Abstract
Extremal point properties are examined for the boundary value problem x(n) + ? n-2 i=0 Ai(t)x(i) = 0, x(i)(0) = x(n-2)(T) = 0, 0?i?n-2, where the Ai's, a characterization for the first extremal point is given in terms of the existence of a solution which is positive with respect to a cone in a Banach space. Also, an existence theorem is obtained for a related nonlinear problem