“…As discussed earlier, the proof of Theorem 1.4, following [1,8], consists of several steps corresponding to transformations of the initial RHP 1.1 implemented successively. For sake of clarity, we present in Section 2 a summary of the analysis of the various steps in each of the four cases, x ≶ 0, t → ±∞ and we show how the RHPs and the respective factorizations are modified to take into account the signs of x and t. In the next Sections (Sections 3 to 7), we provide the details of each step in one case x > 0, t → ∞ as follows.…”