Global bifurcation for discrete competitive systems in the plane
A global bifurcation result is obtained for families of competitive systems of difference equations $x_{n+1} = f_\alpha(x_n,y_n) $ $y_{n+1} = g_\alpha(x_n,y_n)$ where $\alpha$ is a parameter, $f_\alpha$ and $g_\alpha$ are continuous real valued functions on a rectangular domain $\mathcal{R}_\alpha \subset \mathbb{R}^2$ such that $f_\alpha(x,y)$ is non-decreasing in $x$ and non-increasing in $y$, and $g_\alpha(x, y)$ is non-increasing in $x$ and non-decreasing in $y$. A unique interior fixed point is assumed for all values of the parameter $\alpha$. As an application of the main result for competitive systems a global period-doubling bifurcation result is obtained for families of second order difference equations of the type $x_{n+1} = F_\alpha(x_n, x_{n-1}), \quad n=0,1, \ldots $ where $\alpha$ is a parameter, $F_\alpha:\mathcal{I_\alpha}\times \mathcal{I_\alpha} \rightarrow \mathcal{I_\alpha}$ is a decreasing function in the first variable and increasing in the second variable, and $\mathcal{I_\alpha}$ is a interval in $\mathbb{R}$, and there is a unique interior equilibrium point. Examples of application of the main results are also given.