A Systematic Study of Compositional Syntactic Transformer Language Models

Yida Zhao, Hao Xve, Xiang Hu, Kewei Tu


Abstract
Syntactic language models (SLMs) enhance Transformers by incorporating syntactic biases through the modeling of linearized syntactic parse trees alongside surface sentences. This paper focuses on compositional SLMs that are based on constituency parse trees and contain explicit bottom-up composition of constituent representations. We identify key aspects of design choices in existing compositional SLMs and propose a unified framework encompassing both existing models and novel variants. We conduct a comprehensive empirical evaluation of all the variants in our framework across language modeling, syntactic generalization, summarization, and inference efficiency. Based on the experimental results, we make multiple recommendations on the design of compositional SLMs. Our code is released at https://github.com/zhaoyd1/compositional_SLMs.
Anthology ID:
2025.acl-long.350
Volume:
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2025
Address:
Vienna, Austria
Editors:
Wanxiang Che, Joyce Nabende, Ekaterina Shutova, Mohammad Taher Pilehvar
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
7070–7083
Language:
URL:
https://preview.aclanthology.org/ingestion-acl-25/2025.acl-long.350/
DOI:
Bibkey:
Cite (ACL):
Yida Zhao, Hao Xve, Xiang Hu, and Kewei Tu. 2025. A Systematic Study of Compositional Syntactic Transformer Language Models. In Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 7070–7083, Vienna, Austria. Association for Computational Linguistics.
Cite (Informal):
A Systematic Study of Compositional Syntactic Transformer Language Models (Zhao et al., ACL 2025)
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PDF:
https://preview.aclanthology.org/ingestion-acl-25/2025.acl-long.350.pdf