S. Carl et S. Heikkila, Extremality results for first-order discontinuous functional differential equations, COMPUT MATH, 40(10-11), 2000, pp. 1217-1232
In this paper, we derive extremality and comparison results for first-order
explicit and implicit functional differential equations equipped with func
tional initial conditions. Differential equations and initial conditions ma
y involve discontinuities. (C) 2000 Elsevier Science Ltd. All rights reserv
ed.