x1: Learning to Think Adaptively Across Languages and Cultures

Fuente: arXiv
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Main Authors: Ye, Yangfan, Feng, Xiaocheng, Feng, Xiachong, Huang, Yichong, Yuan, Zekun, Huang, Lei, Ma, Weitao, Hong, Qichen, Lu, Yunfei, Tu, Dandan, Qin, Bing
Format: Preprint
Published: 2026
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author Ye, Yangfan
Feng, Xiaocheng
Feng, Xiachong
Huang, Yichong
Yuan, Zekun
Huang, Lei
Ma, Weitao
Hong, Qichen
Lu, Yunfei
Tu, Dandan
Qin, Bing
author_facet Ye, Yangfan
Feng, Xiaocheng
Feng, Xiachong
Huang, Yichong
Yuan, Zekun
Huang, Lei
Ma, Weitao
Hong, Qichen
Lu, Yunfei
Tu, Dandan
Qin, Bing
contents Languages encode distinct abstractions and inductive priors, yet most large language models (LLMs) overlook this diversity by reasoning in a single dominant language. In this work, we introduce x1, a family of reasoning models that can adaptively reason in an advantageous language on a per-instance basis. To isolate the effect of reasoning-language choice, x1 is constructed without expanding the model's knowledge boundaries and is trained by contrasting linguistically distinct reasoning trajectories for the same input. Our extensive experiments demonstrate the benefits of adaptive multilingual reasoning across multilingual mathematical reasoning and culturally grounded tasks. Moreover, our results challenge a simplistic view of scaling laws: while scaling reduces cross-lingual disparities in procedural domains such as math reasoning, it does not eliminate the advantages of culture-associated languages in culturally grounded tasks, as we empirically show that such reasoning enables more efficient and accurate cultural knowledge recall. Overall, our findings establish language choice as a functional component of reasoning, with implications for building more generalist and globally competent reasoning models.
format Preprint
id arxiv_https___arxiv_org_abs_2604_16917
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle x1: Learning to Think Adaptively Across Languages and Cultures
Ye, Yangfan
Feng, Xiaocheng
Feng, Xiachong
Huang, Yichong
Yuan, Zekun
Huang, Lei
Ma, Weitao
Hong, Qichen
Lu, Yunfei
Tu, Dandan
Qin, Bing
Computation and Language
Languages encode distinct abstractions and inductive priors, yet most large language models (LLMs) overlook this diversity by reasoning in a single dominant language. In this work, we introduce x1, a family of reasoning models that can adaptively reason in an advantageous language on a per-instance basis. To isolate the effect of reasoning-language choice, x1 is constructed without expanding the model's knowledge boundaries and is trained by contrasting linguistically distinct reasoning trajectories for the same input. Our extensive experiments demonstrate the benefits of adaptive multilingual reasoning across multilingual mathematical reasoning and culturally grounded tasks. Moreover, our results challenge a simplistic view of scaling laws: while scaling reduces cross-lingual disparities in procedural domains such as math reasoning, it does not eliminate the advantages of culture-associated languages in culturally grounded tasks, as we empirically show that such reasoning enables more efficient and accurate cultural knowledge recall. Overall, our findings establish language choice as a functional component of reasoning, with implications for building more generalist and globally competent reasoning models.
title x1: Learning to Think Adaptively Across Languages and Cultures
topic Computation and Language
url https://arxiv.org/abs/2604.16917