Abstract:
In this paper, we prove that a polynomial vector field of degree $n$ that has two invariant sets, each of which consists of ${n-1}$ pairwise real invariant straight lines, has at most ${2n+4}$ invariant straight lines, where $n$ is odd and $n\geq3$.
Keywords:polynomial vector field, invariant straight line, invariant set, nodal point, rectangle, golden ratio.