Locate and Label: A Two-stage Identifier for Nested Named Entity Recognition

Understand

Named entity recognition (NER) is a well-studied task in natural language processing.

• Traditional NER research only deals with flat entities and ignores nested entities.
• The span-based methods treat entity recognition as a span classification task.
• Although these methods have the innate ability to handle nested NER, they suffer from high computational cost, ignorance of boundary information, under-utilization of the spans that partially match with entities, and difficulties in long entity recognition.