Nontrivial periodicity in discrete delay models of population growth

In this paper, we will study the periodicity in discrete model An+1 = λAn +F(An−m) of population growth, where the delay m is large enough and the nonlinearity F is unimodal function. Actually, we prove that there is a slowly oscillated periodic solution. Our method is Browder nonextremal fixed point theorem.  2005 Elsevier Inc. All rights reserved