SLoW: Select Low-frequency Words! Automatic Dictionary Selection for Translation on Large Language Models

Hongyuan Lu, Zixuan Li, Zefan Zhang, Wai Lam


Abstract
There are more than 7,000 languages around the world, and current Large Language Models (LLMs) only support hundreds of languages. Dictionary-based prompting methods can enhance translation on them, but most methods use all the available dictionaries, which could be expensive. Instead, it will be flexible to have a trade-off between token consumption and translation performance. This paper proposes a novel task called Automatic Dictionary Selection (ADS). The goal of the task is to automatically select which dictionary to use to enhance translation. We propose a novel and effective method which we call Select Low-frequency Words! (SLoW) which selects those dictionaries that have a lower frequency. Our methods have unique advantages. First, there is no need for access to the training data for frequency estimation (which is usually unavailable). Second, it inherits the advantage of dictionary-based methods, where no additional tuning is required on LLMs. Experimental results on 100 languages from FLORES indicate that SLoW surpasses strong baselines, and it can obviously save token usage, with many languages even surpassing the translation performance of the full dictionary baseline.
Anthology ID:
2025.emnlp-main.46
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
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
898–913
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URL:
https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-main.46/
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Bibkey:
Cite (ACL):
Hongyuan Lu, Zixuan Li, Zefan Zhang, and Wai Lam. 2025. SLoW: Select Low-frequency Words! Automatic Dictionary Selection for Translation on Large Language Models. In Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing, pages 898–913, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
SLoW: Select Low-frequency Words! Automatic Dictionary Selection for Translation on Large Language Models (Lu et al., EMNLP 2025)
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