“…For background on Monge-Kantorovich transport, we refer to [2,55,56,60,61]. Recently, a rich literature has emerged around martingale transport and model uncertainty; see [41,53,59] for surveys and, e.g., [1,10,15,16,17,18,23,27,30,31,32,50,52,62] for models in discrete time, [4,14,20,21,24,25,26,36,37,40,49,51,57,58] for continuous time, and [3,7,8,19,22,33,34,35,39,42,46,54] for related Skorokhod embedding and mimicking problems.…”