AdaMame: A Training Recipe for Adaptive Multilingual Reasoning

Dayeon Ki, Kevin Duh, Marine Carpuat


Abstract
While Large Reasoning Models (LRMs) show strong performance in English, they often fail to reason in the language of the query, a phenomenon known as language collapse. Existing RL-based fixes typically add a binary language fidelity reward to the accuracy objective, yet still incur trade-off in accuracy, mid-trace code-switching, and excessive token usage. In this work, we propose AdaMame, a two-stage training recipe for multilingual mathematical reasoning that addresses these limitations by adaptively aligning the reasoning language to the query language without compromising accuracy. The first SFT stage fine-tunes on non-MT reasoning traces across five languages to establish multilingual reasoning capability. In the subsequent RL stage, we introduce AdaMame-GRPO, an adaptation of Group Relative Policy Optimization (GRPO) in which a query-conditioned alignment factor grows progressively during training, guiding the model to first explore diverse reasoning languages before exploiting reasoning in the query language. Evaluated across two benchmarks, two LRMs, and 12 languages, AdaMame-GRPO achieves Pareto-optimal performance across reasoning accuracy, language fidelity, and token efficiency over all baselines, with the strongest gains on out-of-domain, lower-resource languages.
Anthology ID:
2026.emnlp-main.796
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
18490–18511
Language:
URL:
https://aclanthology.org/2026.emnlp-main.796/
DOI:
Bibkey:
Cite (ACL):
Dayeon Ki, Kevin Duh, and Marine Carpuat. 2026. AdaMame: A Training Recipe for Adaptive Multilingual Reasoning. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 18490–18511, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
AdaMame: A Training Recipe for Adaptive Multilingual Reasoning (Ki et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.796.pdf