Step-by-step Instructions and a Simple Tabular Output Format Improve the Dependency Parsing Accuracy of LLMs

Hiroshi Matsuda, Chunpeng Ma, Masayuki Asahara


Abstract
Recent advances in large language models (LLMs) have enabled impressive performance in various tasks. However, standard prompting often struggles to produce structurally valid and accurate outputs, especially in dependency parsing. We propose a novel step-by-step instruction strategy, where universal part-of-speech tagging precedes the prediction of syntactic heads and dependency labels, and a simplified CoNLL-U like output format, our method achieves state-of-the-art accuracy on Universal Dependencies datasets across 17 languages without hallucination or contamination. We further show that multilingual fine-tuning simultaneously improves cross-language generalization performance. Our results highlight the effectiveness of explicit reasoning steps in LLM-based parsing and offer a scalable, format-consistent alternative to bracket-based approaches.
Anthology ID:
2025.iwpt-1.2
Volume:
Proceedings of the 18th International Conference on Parsing Technologies (IWPT, SyntaxFest 2025)
Month:
August
Year:
2025
Address:
Ljubljana, Slovenia
Editors:
Kenji Sagae, Stephan Oepen
Venues:
IWPT | SyntaxFest
SIG:
SIGPARSE
Publisher:
Association for Computational Linguistics
Note:
Pages:
11–19
Language:
URL:
https://preview.aclanthology.org/corrections-2025-08/2025.iwpt-1.2/
DOI:
Bibkey:
Cite (ACL):
Hiroshi Matsuda, Chunpeng Ma, and Masayuki Asahara. 2025. Step-by-step Instructions and a Simple Tabular Output Format Improve the Dependency Parsing Accuracy of LLMs. In Proceedings of the 18th International Conference on Parsing Technologies (IWPT, SyntaxFest 2025), pages 11–19, Ljubljana, Slovenia. Association for Computational Linguistics.
Cite (Informal):
Step-by-step Instructions and a Simple Tabular Output Format Improve the Dependency Parsing Accuracy of LLMs (Matsuda et al., IWPT-SyntaxFest 2025)
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https://preview.aclanthology.org/corrections-2025-08/2025.iwpt-1.2.pdf