Solution (source code)

= Solution

For a supercritical <pitchfork bifurcation>, use $\boxed{x_{n+1}=x_n+\mu x_n-x_n^3}$. The symmetric stable branches $x=\pm\sqrt\mu$ appear for $\mu>0$ as the origin becomes unstable. Replacing the cubic minus sign by plus gives a subcritical <pitchfork bifurcation>.