Extending Automatic Machine Translation Evaluation to Book-Length Documents

Kuang-Da Wang, Shuoyang Ding, Chao-Han Huck Yang, Ping-Chun Hsieh, Wen-Chih Peng, Vitaly Lavrukhin, Boris Ginsburg


Abstract
Despite Large Language Models (LLMs) demonstrating superior translation performance and long-context capabilities, evaluation methodologies remain constrained to sentence-level assessment due to dataset limitations, token number restrictions in metrics, and rigid sentence boundary requirements. We introduce SEGALE, an evaluation scheme that extends existing automatic metrics to long-document translation by treating documents as continuous text and applying sentence segmentation and alignment methods. Our approach enables previously unattainable document-level evaluation, handling translations of arbitrary length generated with document-level prompts while accounting for under-/over-translations and varied sentence boundaries. Experiments show our scheme significantly outperforms existing long-form document evaluation schemes, while being comparable to evaluations performed with groundtruth sentence alignments. Additionally, we apply our scheme to book-length texts and newly demonstrate that many open-weight LLMs fail to effectively translate documents at their reported maximum context lengths.
Anthology ID:
2025.emnlp-main.1645
Volume:
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Month:
November
Year:
2025
Address:
Suzhou, China
Editors:
Christos Christodoulopoulos, Tanmoy Chakraborty, Carolyn Rose, Violet Peng
Venue:
EMNLP
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Publisher:
Association for Computational Linguistics
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Pages:
32311–32327
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URL:
https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-main.1645/
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Cite (ACL):
Kuang-Da Wang, Shuoyang Ding, Chao-Han Huck Yang, Ping-Chun Hsieh, Wen-Chih Peng, Vitaly Lavrukhin, and Boris Ginsburg. 2025. Extending Automatic Machine Translation Evaluation to Book-Length Documents. In Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing, pages 32311–32327, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
Extending Automatic Machine Translation Evaluation to Book-Length Documents (Wang et al., EMNLP 2025)
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