“…Similarly to (6.18) the objective in the Lagrange dual problem has Lipschitz gradient, yet the challenge is that the feasible set in the dual problem is not bounded. Despite that it is possible to obtain accelerated primal-dual methods [195,196,199,200,201,202,203,204,155,205,132,206]. In particular, this allows to obtain improved complexity bounds for different types of optimal transport problems [202,207,205,140,208,209,210,211,212].…”