Detecting Contradiction in Text by Using Lexical Mismatch and Structural Similarity.
Daniel Andrade, Masaaki Tsuchida, Takashi Onishi, Kai Ishikawa · 2013
Detecting contradicting statements is a crucial sub-problem for ltering textual entailment pairs. Given two text pairs T1 and T2 that are topically related, the task is to nd whether the two statements are in contrast to each other, or not. In many situations a mismatch in named entities or numerical expressions is a strong clue for a contradiction between T1 and T2. However, if the dependency parse trees are quite dierent, and the words of T1 and T2 cannot be aligned well, then this indicates that a lexical mismatch is not sucient to conclude contradiction of T1 and T2. We present a new method that assumes the higher the structural similarity of two sentences, the higher the chance that a con-tradiction on the word level indicates contradiction on the sentence level. We participated in two subtasks of RITE2 at NTCIR-10 which contain many contradicting statements in a real world setting. Our system became second place in the ExamBC subtask (formal run, ocial result), and rst place in the ExamSearch subtask (formal run, unocial re-sult). We show that our proposed method contributed to the improvement in both tasks.