上游任务 - 关系抽取
https://zhuanlan.zhihu.com/p/77868938
先抽取实体，再判断关系
R-BERT: https://blog.csdn.net/xiaowopiaoling/article/details/105679350, Enriching Pre-trained Language Model with Entity Information for Relation Classification
联合抽取
TPLinker： https://github.com/131250208/TPlinker-joint-extraction， TPLinker: Single-stage Joint Extraction of Entities and Relations Through Token Pair Linking， https://blog.csdn.net/li_jiaoyang/article/details/111315300
https://github.com/weizhepei/CasRel， A Novel Cascade Binary Tagging Framework for Relational Triple Extraction， https://zhuanlan.zhihu.com/p/143591841