2.I.7E

Dynamical Systems
Part II, 2007

Find and classify the fixed points of the system

x˙=(1x2)yy˙=x(1y2)\begin{aligned} &\dot{x}=\left(1-x^{2}\right) y \\ &\dot{y}=x\left(1-y^{2}\right) \end{aligned}

What are the values of their Poincaré indices? Prove that there are no periodic orbits. Sketch the phase plane.