Our method uses reordering graphs to represent all phrase segmentations of parallel sentence pairs, and then gets the fractional counts of bilingual phrases for orientations from reordering graphs in an inside-outside fashion.
the phrase-based reordering model (tillmann, 2004) determines the presence of the adjacent bilingual phrase located in position (s − 1, v + 1) and then treats the orientation of bp as S. Given no constraint on maximum phrase length, the hierarchical phrase reordering model (Galley and Manning, 2008) also analyzes the adjacent bilingual phrases for bp and identifies its orientation as S. given a bilingual phrase, the abovementioned models just consider the presence of an adjacent bilingual phrase rather than the number of adjacent bilingual phrases.