ERICA: Improving Entity and Relation Understanding for Pre-trained Language Models via Contrastive Learning

• DOI: 10.18653/v1/2021.acl-long.260
• Publication Date: 2021-07-27T01:42:51Z
• Authors: Yujia Qin; Yankai Lin; Ryuichi Takanobu; Zhiyuan Liu; Peng Li; Heng Ji; Minlie Huang; Maosong Sun; Jie Zhou
• Keywords: FOS: Computer and information sciences; Computer Science - Computation and Language; Artificial Intelligence (cs.AI); Computer Science - Artificial Intelligence; 0202 electrical engineering, electronic engineering, information engineering; 02 engineering and technology; Computation and Language (cs.CL)

Pre-trained Language Models (PLMs) have shown superior performance on various downstream Natural Language Processing (NLP) tasks. However, conventional pre-training objectives do not explicitly model relational facts in text, which are crucial for textual understanding. To address this issue, we propose a novel contrastive learning framework ERICA to obtain a deep understanding of the entities and their relations in text. Specifically, we define two novel pre-training tasks to better understand entities and relations: (1) the entity discrimination task to distinguish which tail entity can be inferred by the given head entity and relation; (2) the relation discrimination task to distinguish whether two relations are close or not semantically, which involves complex relational reasoning. Experimental results demonstrate that ERICA can improve typical PLMs (BERT and RoBERTa) on several language understanding tasks, including relation extraction, entity typing and question answering, especially under low-resource settings.<br/>Accepted by ACL-IJCNLP 2021 main conference<br/>