Vector Fields in the Interior of Kupka–Smale Systems Satisfy Axiom A

In 1994, S. Hu conjectured in his paper (1994, Trans. Amer. Math. Soc.342, 753–772) that Axiom A systems are dense in the interior of Kupka–Smale systems. We will show that if X is in the interior of Kupka–Smale systems, then X satisfies Axiom A.