Unifying emotion-oriented and cause-oriented predictions for emotion-cause pair extraction

Guimin Hu, Yi Zhao, Guangming Lu

Abstract: Emotion-cause pair extraction (ECPE) is an extraction task aiming to simultaneously identify the emotions and causes from the text without emotion annotations. Let ci<math><msub is="true"><mrow is="true"><mi is="true">c</mi></mrow><mrow is="true"><mi is="true">i</mi></mrow></msub></math> and cj<math><msub is="true"><mrow is="true"><mi is="true">c</mi></mrow><mrow is="true"><mi is="true">j</mi></mrow></msub></math> represent the emotion clause and the cause clause of a document, respectively, and we can predict one from the other and vice versa. Previous works fail to take advantage of this bidirectional opportunity. We refer to the prediction from ci<math><msub is="true"><mrow is="true"><mi is="true">c</mi></mrow><mrow is="true"><mi is="true">i</mi></mrow></msub></math> to cj<math><msub is="true"><mrow is="true"><mi is="true">c</mi></mrow><mrow is="true"><mi is="true">j</mi></mrow></msub></math>, i.e., ci→cj<math><mrow is="true"><msub is="true"><mrow is="true"><mi is="true">c</mi></mrow><mrow is="true"><mi is="true">i</mi></mrow></msub><mo is="true">→</mo><msub is="true"><mrow is="true"><mi is="true">c</mi></mrow><mrow is="true"><mi is="true">j</mi></mrow></msub></mrow></math>, as an emotion-oriented cause prediction (EoCP) task and the prediction from cj<math><msub is="true"><mrow is="true"><mi is="true">c</mi></mrow><mrow is="true"><mi is="true">j</mi></mrow></msub></math> to ci<math><msub is="true"><mrow is="true"><mi is="true">c</mi></mrow><mrow is="true"><mi is="true">i</mi></mrow></msub></math>, i.e., cj→ci<math><mrow is="true"><msub is="true"><mrow is="true"><mi is="true">c</mi></mrow><mrow is="true"><mi is="true">j</mi></mrow></msub><mo is="true">→</mo><msub is="true"><mrow is="true"><mi is="true">c</mi></mrow><mrow is="true"><mi is="true">i</mi></mrow></msub></mrow></math>, as a cause-oriented emotion prediction (CoEP) task. After redefining the ECPE task, we propose a novel unified architecture for ECPE, which incorporates EoCP and CoEP as cells and unifies them into a single-chain architecture. Additionally, we redefine emotion-cause pair extraction as a closed-loop structure detection problem to alleviate the mismatch between emotion and cause clauses. To enhance the training of the architecture, we provide a procedure for estimating the confidence of the extraction system for its emotion-cause pairs. We demonstrate the superiority of our proposed model through extensive experiments on two public datasets, achieving a new state-of-the-art performance. Furthermore, our method particularly achieves significant improvements in multiple emotion-cause pair extraction.