“…Furthermore, exact filtering algorithms, among them integer programming, 21 dead-end elimination (DEE), 12,13,23 and A*, 24 can advance the R 4 process by eliminating possibilities. 17 For example, in DEE the relative global energy, E global , of an IP is composed of the linear sum of the energy contributions from the backbone, the self and interaction with backbone energy, E(i r ), of rotamer, r, at its position, i, and its pairwise interaction energy with rotamer at nearby position, j: best case, arrangement of rotamer, i r , still has a higher energy than the maximum energy, or worst case, arrangement of an alternate rotamer, i t :…”