“…The popular methods of constructing an ambiguity set basically focus on the moment-based ambiguity set, which is constructed by certain moment information (see, for example, [16][17][18][19][20][21][22]), and the metric-based one, which is defined as a "ball" in the sense of a certain probability metric such as the Prohorov metric (see [23]), the goodness-of-fit (see [24]), likelihood function (see [25]), φ-divergence (see, for example, [26][27][28][29][30]), Kullback-Leibler (KL) divergence (see, for example, [31,32]) and so forth. In particular, due to the outstanding properties of Wasserstein distance, defined as follows, Wasserstein distance is attracting a growing interest in DRO recently (see, for example, [33][34][35][36][37]).…”