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Building Multilingual Bridges: Data Mixing as the Pillar of Generalization for In-Language Reasoning

arxiv.org/abs/2609.10445

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Updated 45 min ago · first seen 11 Sept 2026

paper_01M294WYECGNC61QN7FPQKZRC4

Published
9 Sept 2026
T2 · 48 min ago
arXiv
2609.10445
T2 · 48 min ago

Abstract

Reasoning language models have made substantial advances on a variety of complex tasks, yet their capabilities remain overwhelmingly English-centric: models primarily reason in English regardless of the language they are prompted in. This is inaccessible for non-English-speaking users, risks losing the intent of the original question, and forgoes knowledge more readily expressed in the target language. In this work, we advance L2 reasoning, the ability of a model to reason consistently in the language of the user's prompt, thus building an in-language bridge between the prompt and the answer. We approach this problem from a data-centric angle, investigating how to optimize data composition and scheduling in SFT for reasoning generalization. Building Tiny Aya L2-Thinker at 3.35B scale, we achieve an L2 reasoning rate above 93% across 60 languages on 6 benchmarks spanning math, commonsense reasoning, instruction following, open-ended generation, and cultural reasoning while keeping performance strong. We show the path to generalizing L2 reasoning to held-out languages goes through broader language coverage, readily available multilingual non-reasoning data, and a sufficient English reasoning backbone. These findings indicate that reasoning is a language-agnostic behavior that can be transferred across typologically diverse languages through careful data mixing and without requiring reasoning supervision in every target language. We release our model weights and multilingual reasoning data to support further research on accessible, in-language reasoning.

Authors 8

Mehrnaz Mofakhami, Ananya Sahu, Alejandro R. Salamanca, Daniel D'souza, Alexandre Berard, Thomas Euyang, Marzieh Fadaee, Julia Kreutzer

Specification

Official page

Source:Hugging Face Hub (public pages, model cards, papers)T2observed 48 min agomedium

arXiv id
2609.10445

Source:Hugging Face Hub (public pages, model cards, papers)T2observed 48 min agomedium

Hf paper url
https://huggingface.co/papers/2609.10445

Source:Hugging Face Hub (public pages, model cards, papers)T2observed 48 min agomedium

Hf comments
1

Source:Hugging Face Hub (public pages, model cards, papers)T2observed 45 min agomedium

Upvotes
1

Source:Hugging Face Hub (public pages, model cards, papers)T2observed 45 min agomedium

Published
9 Sept 2026

Source:Hugging Face Hub (public pages, model cards, papers)T2observed 48 min agomedium

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Provenance

Attributed facts

9

Source tiers

T29

Freshest observation

45 min ago

Conflicts

None