Subsequently, the siblings under S in the resulting tree are permuted, "must" is reordered across the whole clause and placed to the first position (see Figure 3c).
the model in (Li et al., 2007) is explicitly aimed at long-distance reorderings (English-Chinese), prunes the alignment matrix gradually to fit the source syntactic parse and employs Maximum-Entropy modeling to choose the optimal local ITG-like permutation step of sister subtrees but interleaves that step with a translation step.