Backpropagating through Structured Argmax using a SPIGOT

Hao Peng, Sam Thomson, Noah A. Smith


Abstract
We introduce structured projection of intermediate gradients (SPIGOT), a new method for backpropagating through neural networks that include hard-decision structured predictions (e.g., parsing) in intermediate layers. SPIGOT requires no marginal inference, unlike structured attention networks and reinforcement learning-inspired solutions. Like so-called straight-through estimators, SPIGOT defines gradient-like quantities associated with intermediate nondifferentiable operations, allowing backpropagation before and after them; SPIGOT’s proxy aims to ensure that, after a parameter update, the intermediate structure will remain well-formed. We experiment on two structured NLP pipelines: syntactic-then-semantic dependency parsing, and semantic parsing followed by sentiment classification. We show that training with SPIGOT leads to a larger improvement on the downstream task than a modularly-trained pipeline, the straight-through estimator, and structured attention, reaching a new state of the art on semantic dependency parsing.
Anthology ID:
P18-1173
Volume:
Proceedings of the 56th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2018
Address:
Melbourne, Australia
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1863–1873
Language:
URL:
https://aclanthology.org/P18-1173
DOI:
10.18653/v1/P18-1173
Bibkey:
Cite (ACL):
Hao Peng, Sam Thomson, and Noah A. Smith. 2018. Backpropagating through Structured Argmax using a SPIGOT. In Proceedings of the 56th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 1863–1873, Melbourne, Australia. Association for Computational Linguistics.
Cite (Informal):
Backpropagating through Structured Argmax using a SPIGOT (Peng et al., ACL 2018)
Copy Citation:
PDF:
https://preview.aclanthology.org/remove-xml-comments/P18-1173.pdf
Note:
 P18-1173.Notes.pdf
Presentation:
 P18-1173.Presentation.pdf
Video:
 https://vimeo.com/285804853
Code
 Noahs-ARK/SPIGOT