Copyright © 2010 Kexue Zhang and Xinzhi Liu. This is an open access article distributed under the
Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This paper investigates the nonlinear boundary value problem for a class of first-order impulsive functional differential equations. By establishing a comparison result and utilizing the method of upper
and lower solutions, some criteria on the existence of extremal solutions as well as the unique solution
are obtained. Examples are discussed to illustrate the validity of the obtained results.