Which Language Should a Skeleton Speak? Language Choices in Multilingual Reasoning

HyeonSeok Lim, SeungWoo Song, Inho Won, Hoyun Song, Jihyo Kim, KyungTae Lim


Abstract
Skeleton-based reasoning prompting is a promising training-free approach for structuring LLM reasoning, but prior work largely assumes an English-centric setting. We propose the Language-Aware Skeleton Exploration Framework () to study skeleton-language choice in multilingual mathematical reasoning. Across math benchmarks, model scales, and languages, we show that English skeletons yield a small positive tendency on average, most visible for smaller models and low-resource languages. However, few language-level gains remain significant after correction, and English is not universally optimal. Combining greedy decoding, multi-rollout evaluation, translation ablation, and cross-benchmark validation, we further find three patterns of skeleton-language effects: directionally consistent, evaluation- and benchmark-dependent, and asymmetric negative. These effects cannot be fully explained by generation quality alone. Overall, skeleton language is a context-dependent design variable that requires multi-level exploration. All resources are released[<https://github.com/lhsstn/LASEF>].
Anthology ID:
2026.findings-emnlp.1500
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:
31933–31957
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1500/
DOI:
Bibkey:
Cite (ACL):
HyeonSeok Lim, SeungWoo Song, Inho Won, Hoyun Song, Jihyo Kim, and KyungTae Lim. 2026. Which Language Should a Skeleton Speak? Language Choices in Multilingual Reasoning. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 31933–31957, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Which Language Should a Skeleton Speak? Language Choices in Multilingual Reasoning (Lim et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1500.pdf