## Positive periodic solutions for discrete population models.(English)Zbl 1053.39027

The authors study delay discrete population models of the form $x(n+1)=a(n)x(n)+\lambda h(n)f(x(n-\tau(n))), \;n\in \mathbb{Z}, \tag{E}$ where $$\{a(n)\}_{n\in \mathbb{Z}}$$ and $$\{h(n)\}_{n\in \mathbb{Z}}$$ are positive $$\omega$$-periodic sequences, $$\{\tau(n)\}_{n\in \mathbb{Z}}$$ is an integer valued $$\omega$$-periodic sequence and $$\lambda$$ is a positive parameter. By using Krasnosel’skij’s fixed point theorem, some existence criteria are established for the periodic solutions of the equation (E).

### MSC:

 39A11 Stability of difference equations (MSC2000) 92D25 Population dynamics (general)