A typical RE setting is given a sentence marked by two entities, and models need to classify the sentence into one of the predefined relations. A complete relation extraction system consists of:

• named entity recognizer to identify named entities
• Entity linker to link entities to existing knowledge graphs
• Relational classifier to determine relations between entities by given context Identifying the relation is the most crucial and most difficult task because it requires models to understand the semantics of the context. Therefore, RE generally focuses on researching the relational classification side of the RE systems.