Figure 4

Automatic ordering of builders and restraints involved in sampling a three-residue peptide. (A) shows the builders and their output coordinates, C _α positional restraints and the coordinates they test. NB (N-anchor-builder), PB (ϕ, ψ-sampling based peptide builder), RPB (PB-like, but in reverse direction), SC (backbone dependent sidechain builder) are used. A builder points into the coordinates it computes and is pointed at by the output coordinates of the builders it depends on. Restraints contain the coordinates they test. (B) On left is the dependence digraph on builders and restraints in (A). A builder node depends upon the builder node it is pointed from. A restraint node is connected to a builder after execution of which it is possible to execute the restraint. Topological sort (as described in text) on this digraph results (on right) in a linear forward order (black) and fallback order (red) on builders.