To achieve this goal, we first use the structural alignment consistency (SAC) (Su et al., 2015) that is the basis of our model to classify resultant nodes of semantic compositions into two categories.
if the node n covers a sub-phrase, and there exists a sub-phrase in the other language such that these two sub-phrases are consistent with word alignments (Och and Ney, 2003), we say n satisfies the structural alignment consistency, and it is referred to as an SAC node, otherwise, it is a non-SAC node.