Coordinate Structure Alignment of Patent Claims by LLMs

Tsukasa Ishimaru, Takehito Utsuro, Masaaki Nagata


Abstract
This paper proposes an LLM-based method for cross-lingual alignment of coordinate structures in Japanese–English and Chinese–English patent claims. The approach has two components. First, we construct task-specific alignment datasets by translating Penn Treebank-3 English sentences into Japanese and Chinese and projecting coordinate-structure annotations using syntactic parse trees, word alignments, and the GHKM algorithm. Second, we formulate alignment as a TANL-based text generation task in which LLMs generate the target sentence with the corresponding span tagged. Although the training data are derived from a general-domain corpus, evaluation is conducted on manually annotated real patent claims. Across four translation directions, the proposed approach consistently outperforms SpanAlign, an encoder-based alignment baseline built on SQuAD-style cross-lingual span prediction and ILP-based alignment. Controlled analyses show that the TANL formulation improves performance independently of supervised fine-tuning and that automatically generated demonstrations achieve performance close to manually constructed examples in the tested 3-shot setting. Supervised fine-tuning with the automatically constructed datasets further improves open-weight LLMs, with the best fine-tuned model in each direction achieving an F1 score above 0.8.
Anthology ID:
2026.findings-emnlp.419
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
8830–8845
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.419/
DOI:
Bibkey:
Cite (ACL):
Tsukasa Ishimaru, Takehito Utsuro, and Masaaki Nagata. 2026. Coordinate Structure Alignment of Patent Claims by LLMs. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 8830–8845, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Coordinate Structure Alignment of Patent Claims by LLMs (Ishimaru et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.419.pdf