A Differentiable Relaxation of Graph Segmentation and Alignment for AMR Parsing

Chunchuan Lyu, Shay B. Cohen, Ivan Titov


Abstract
Abstract Meaning Representations (AMR) are a broad-coverage semantic formalism which represents sentence meaning as a directed acyclic graph. To train most AMR parsers, one needs to segment the graph into subgraphs and align each such subgraph to a word in a sentence; this is normally done at preprocessing, relying on hand-crafted rules. In contrast, we treat both alignment and segmentation as latent variables in our model and induce them as part of end-to-end training. As marginalizing over the structured latent variables is infeasible, we use the variational autoencoding framework. To ensure end-to-end differentiable optimization, we introduce a differentiable relaxation of the segmentation and alignment problems. We observe that inducing segmentation yields substantial gains over using a ‘greedy’ segmentation heuristic. The performance of our method also approaches that of a model that relies on the segmentation rules of Lyu and Titov (2018), which were hand-crafted to handle individual AMR constructions.
Anthology ID:
2021.emnlp-main.714
Volume:
Proceedings of the 2021 Conference on Empirical Methods in Natural Language Processing
Month:
November
Year:
2021
Address:
Online and Punta Cana, Dominican Republic
Editors:
Marie-Francine Moens, Xuanjing Huang, Lucia Specia, Scott Wen-tau Yih
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
9075–9091
Language:
URL:
https://aclanthology.org/2021.emnlp-main.714
DOI:
10.18653/v1/2021.emnlp-main.714
Bibkey:
Cite (ACL):
Chunchuan Lyu, Shay B. Cohen, and Ivan Titov. 2021. A Differentiable Relaxation of Graph Segmentation and Alignment for AMR Parsing. In Proceedings of the 2021 Conference on Empirical Methods in Natural Language Processing, pages 9075–9091, Online and Punta Cana, Dominican Republic. Association for Computational Linguistics.
Cite (Informal):
A Differentiable Relaxation of Graph Segmentation and Alignment for AMR Parsing (Lyu et al., EMNLP 2021)
Copy Citation:
PDF:
https://aclanthology.org/2021.emnlp-main.714.pdf
Video:
 https://aclanthology.org/2021.emnlp-main.714.mp4
Data
LDC2017T10