Therefore, we first create two sets of RHD from P and H to denote their corresponding structures, and then perform comparison between triplets in P and those in H. Accordingly, two RHD triplets should be aligned if their relations are related and their head-words are aligned (e.g., the triplets with the same indexes are aligned in Figure 1).
when two RHD triplets are compared, each part of RHD triplet (i.e., Relation, Head, and Dependent) should be compared separately.