Multilingual Chain-of-Thought Compression via Cross-Lingual Distillation

Jiarui Wan, Songming Zhang, Yufeng Chen


Abstract
Chain-of-thought reasoning improves the performance of large language models on complex tasks but often produces overly verbose outputs, leading to increased inference cost. This issue is exacerbated in multilingual settings, where differences in tokenization and linguistic structure result in inconsistent compression performance across languages. Existing methods are largely English-centric and tend to suffer from accuracy degradation, especially in low-resource languages.We propose Multilingual Chain-of-thought Compression via Cross-lingual Distillation (MCD), a unified framework that addresses these challenges through both data construction and optimization. MCD builds a cross-lingually aligned dataset using a translation-with-verification pipeline and difficulty-aware sampling, and employs a reinforcement training strategy that combines supervised fine-tuning with direct preference optimization to encourage concise yet sufficient reasoning.Experiments on multilingual mathematical benchmarks show that MCD consistently reduces reasoning length while maintaining competitive accuracy, and significantly improves robustness in low-resource languages.
Anthology ID:
2026.mellm-1.8
Volume:
Proceedings of the 1st Workshop on Multilinguality in the Era of Large Language Models (MeLLM 2026)
Month:
July
Year:
2026
Address:
San Diego, United States
Editors:
Kaiyu Huang, Fengran Mo, Pinzhen Chen, Meng Jiang
Venues:
MeLLM | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
83–91
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.mellm-1.8/
DOI:
Bibkey:
Cite (ACL):
Jiarui Wan, Songming Zhang, and Yufeng Chen. 2026. Multilingual Chain-of-Thought Compression via Cross-Lingual Distillation. In Proceedings of the 1st Workshop on Multilinguality in the Era of Large Language Models (MeLLM 2026), pages 83–91, San Diego, United States. Association for Computational Linguistics.
Cite (Informal):
Multilingual Chain-of-Thought Compression via Cross-Lingual Distillation (Wan et al., MeLLM 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.mellm-1.8.pdf