A Supplementary Material

In what follows, we give some details of content omitted in the paper due to space limit. The proof approach is based on Nagumo's Theorem, which gives necessary and sufficient conditions Definition 2. Let A be a closed set. The following is a fundamental preliminary result for establishing positive invariance. Proposition 2. F or any x 2 @ D, we have T Lemma 2 is a consequence of Proposition 2. For ease of exposition, we first reproduce the lemma First, suppose that condition (i) holds. Next, suppose that condition (ii) holds.