Abstract
This paper presents Pyramid, a novel layered model for Nested Named Entity Recognition (nested NER). In our approach, token or text region embeddings are recursively inputted into L flat NER layers, from bottom to top, stacked in a pyramid shape. Each time an embedding passes through a layer of the pyramid, its length is reduced by one. Its hidden state at layer l represents an l-gram in the input text, which is labeled only if its corresponding text region represents a complete entity mention. We also design an inverse pyramid to allow bidirectional interaction between layers. The proposed method achieves state-of-the-art F1 scores in nested NER on ACE-2004, ACE-2005, GENIA, and NNE, which are 80.27, 79.42, 77.78, and 93.70 with conventional embeddings, and 87.74, 86.34, 79.31, and 94.68 with pre-trained contextualized embeddings. In addition, our model can be used for the more general task of Overlapping Named Entity Recognition. A preliminary experiment confirms the effectiveness of our method in overlapping NER.- Anthology ID:
- 2020.acl-main.525
- Volume:
- Proceedings of the 58th Annual Meeting of the Association for Computational Linguistics
- Month:
- July
- Year:
- 2020
- Address:
- Online
- Editors:
- Dan Jurafsky, Joyce Chai, Natalie Schluter, Joel Tetreault
- Venue:
- ACL
- SIG:
- Publisher:
- Association for Computational Linguistics
- Note:
- Pages:
- 5918–5928
- Language:
- URL:
- https://preview.aclanthology.org/add_missing_videos/2020.acl-main.525/
- DOI:
- 10.18653/v1/2020.acl-main.525
- Cite (ACL):
- Jue Wang, Lidan Shou, Ke Chen, and Gang Chen. 2020. Pyramid: A Layered Model for Nested Named Entity Recognition. In Proceedings of the 58th Annual Meeting of the Association for Computational Linguistics, pages 5918–5928, Online. Association for Computational Linguistics.
- Cite (Informal):
- Pyramid: A Layered Model for Nested Named Entity Recognition (Wang et al., ACL 2020)
- PDF:
- https://preview.aclanthology.org/add_missing_videos/2020.acl-main.525.pdf
- Code
- LorrinWWW/Pyramid + additional community code
- Data
- GENIA, NNE