“…There is a large body of literature on the special case of problem (1) corresponding to Lagrangian relaxation of discrete optimization problems, see e.g. [31,26,13,22,14,24,28,16,19,25,18,30,29,32]. Some of these method apply only to MAP inference problems in pairwise (or low-order) graphical models, because they need to compute marginals in tree-structured subproblems [13,14,25] or because they explicitly exploit the fact that the relaxation can be described by polynomial many constraints [28,19,30,29].…”