“…The first main theorem of this paper states as follows: For more precise statement, see Theorem 4.1. Concerning the proof, the idea is to adapt the recent approach of using local energy and weighted Strichartz estimates, which has been very successful in the recent resolution of the Strauss conjecture on various space-times, including Schwarzschild/Kerr black-hole space-times ( [2], [4], [9], [12]). In particular, we revisit the proof of [12, Theorem 4.1] to extract the key weighted Strichartz estimates, Lemma 3.2, which, combined with the local energy estimates ( [1], [14], [18], [10]), is good enough to treat the lower order terms in (1.3) in a perturbative way.…”