Multiple positive solutions for boundary value problems of second-order delay differential equations

We use a fixed-point index theorem in cones to study the existence of multiple positive solutions for boundary value problems of second-order delay differential equations with the form y"(x) + f(x, y(x - r)) = 0, 0 < x < 1, y(x) = 0, -r less than or equal to x less than or equal to 0, y(1) = 0, where 0 < r < 1/4 is suitably small. The main result here is the generalization of Liu and Li[1] for ordinary differential equations. (C) 2002 Elsevier Science Ltd. All rights reserved.