SmBoP: Semi-autoregressive Bottom-up Semantic Parsing

Ohad Rubin, Jonathan Berant


Abstract
The de-facto standard decoding method for semantic parsing in recent years has been to autoregressively decode the abstract syntax tree of the target program using a top-down depth-first traversal. In this work, we propose an alternative approach: a Semi-autoregressive Bottom-up Parser (SmBoP) that constructs at decoding step t the top-K sub-trees of height ≤ t. Our parser enjoys several benefits compared to top-down autoregressive parsing. From an efficiency perspective, bottom-up parsing allows to decode all sub-trees of a certain height in parallel, leading to logarithmic runtime complexity rather than linear. From a modeling perspective, a bottom-up parser learns representations for meaningful semantic sub-programs at each step, rather than for semantically-vacuous partial trees. We apply SmBoP on Spider, a challenging zero-shot semantic parsing benchmark, and show that SmBoP leads to a 2.2x speed-up in decoding time and a ~5x speed-up in training time, compared to a semantic parser that uses autoregressive decoding. SmBoP obtains 71.1 denotation accuracy on Spider, establishing a new state-of-the-art, and 69.5 exact match, comparable to the 69.6 exact match of the autoregressive RAT-SQL+GraPPa.
Anthology ID:
2021.naacl-main.29
Volume:
Proceedings of the 2021 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies
Month:
June
Year:
2021
Address:
Online
Venue:
NAACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
311–324
Language:
URL:
https://aclanthology.org/2021.naacl-main.29
DOI:
10.18653/v1/2021.naacl-main.29
Bibkey:
Cite (ACL):
Ohad Rubin and Jonathan Berant. 2021. SmBoP: Semi-autoregressive Bottom-up Semantic Parsing. In Proceedings of the 2021 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies, pages 311–324, Online. Association for Computational Linguistics.
Cite (Informal):
SmBoP: Semi-autoregressive Bottom-up Semantic Parsing (Rubin & Berant, NAACL 2021)
Copy Citation:
PDF:
https://aclanthology.org/2021.naacl-main.29.pdf
Video:
 https://aclanthology.org/2021.naacl-main.29.mp4
Code
 OhadRubin/SmBop
Data
SPIDER