“…Given two random variables X ∼ µ and Y ∼ ν, where µ, ν are probability measures on R d , d ≥ 1, the problem of finding a "nice" map T 0 (•) such that T 0 (X) ∼ ν has numerous applications in machine learning such as domain adaptation and data integration [67,54,38,37,41,122], dimension reduction [72,13,98], generative models [66,89,96,120], to name a few. Of particular interest is the case when T 0 (•) is obtained by minimizing a cost function, a line of work initiated by Gaspard Monge [106] in 1781 (see (1.1) below), in which case T 0 (•) is termed an optimal transport (OT) map and has applications in shape matching/transfer problems [52,131,32,117], Bayesian statistics [118,51,83,88], econometrics [60,16,31,56,50], nonparametric statistical inference [44,123,124,43,42]; also see [139,140,121] for book-length treatments on the subject. In this paper, we will focus on the OT map obtained using the standard Euclidean cost function, i.e., T 0 := argmin…”