An Object Detection Framework for Span Extraction in Question Answering

Abstract

Machine Reading Comprehension(MRC), including a series of tasks that test the ability of models to understand natural language, has received quite a few attention in Natural Language Processing(NLP). Most existing works deal with MRC tasks by exploiting the expression capability of neural networks. Some of them have achieved impressive performance. Despite the rapid iteration of the models used, few work have focused on output layer and prediction method of answer span - also known as span extraction. In this paper, we focus on span extraction in the Question Answering(QA) task. A cross-sectional comparison of widely used span extraction methods is presented, with their strengths and weaknesses noted in detail. Furthermore, inspired by Faster R-CNN, we propose a brand new span extraction method. Experiment results show that our proposed method outperforms existing span extraction methods on both English and Chinese MRC tasks.