PERIODIC SOLUTIONS IN A DELAYED PREDATOR-PREY MODEL WITH NONMONOTONIC FUNCTIONAL RESPONSE

摘要

By using the continuation theorem of coincidence degree theory, the existence of a positive periodic solution for a delayed predator-prey model with nonmonotonic functional response (t) = (t)(a (t) – b(t)x (t)) – (x(t)y(t))/(m~2+ cx(t) x~2(t)), y'(t) = y(t)(μ(t)x(t – τ))/(m~2 cx (t – τ)+x~2 (t – τ)) – d(t)), is established, where a(t), b(t), μ(t) and d(t) are all positive periodic continuous functions with period w > 0, c > 0, m > 0 and τ is a nonnegative constant. In particular, our result improves one former conclusion.