Qwen3-FR-Swap

Qwen3-8B-FR-Swap is a Layer Swap model built on top of lightonai/Qwen3-8B-FR: the middle transformer layers (L13–L22) of the English specialist lightonai/Qwen3-8B-EN have been transplanted into the French native specialist. The resulting model reasons natively in French while inheriting the stronger reasoning core of the English specialist.

It is released alongside the paper Rethinking the Multilingual Reasoning Gap with Layer Swap.

Model details

• Base model: Qwen/Qwen3-8B-Base
• Construction: Training-free Layer Swap — layers L13–L22 of Qwen3-8B-EN transplanted into Qwen3-8B-FR
• Language: French (CoT and answer)
• Context length: 32,768 tokens
• Dataset (underlying specialists): lightonai/Dolci-Think-SFT-32B-Multilingual

[!NOTE] The model was trained on data derived from allenai/Dolci-Think-SFT-32B, released under the ODC-BY-1.0 license.

Related models

This model is part of a French specialist trio designed to study the native reasoning gap:

Evaluation

All scores are mean accuracy (%) on the French version of each benchmark, with sample standard deviation across runs. AIME 24/25 is averaged over 30 runs; the others over 10 runs, using the recommended generation parameters.

Benchmarks used:

• lightonai/gpqa_diamond_multilingual
• lightonai/aime24_multilingual
• lightonai/aime25_multilingual
• lightonai/HumanEvalPlus_multilingual
• lightonai/mgsm-rev2
• CohereLabs/Global-MMLU-Lite

Usage

from transformers import AutoModelForCausalLM, AutoTokenizer

model_name = "lightonai/Qwen3-8B-FR-Swap"
tokenizer = AutoTokenizer.from_pretrained(model_name)
model = AutoModelForCausalLM.from_pretrained(model_name, torch_dtype="auto", device_map="auto")

messages = [{"role": "user", "content": "Résous : 24 × 17 = ?"}]
inputs = tokenizer.apply_chat_template(messages, return_tensors="pt", add_generation_prompt=True).to(model.device)

outputs = model.generate(inputs, max_new_tokens=32768, temperature=1.0, top_p=0.95, top_k=20)
print(tokenizer.decode(outputs[0][inputs.shape[-1]:], skip_special_tokens=True))

Recommended sampling: temperature=1.0, top_p=0.95, top_k=20, min_p=0.

Citation

If you find our work helpful, feel free to give us a cite.

@misc{lasbordes2026rethinking,
  title        = {Rethinking the Multilingual Reasoning Gap with Layer Swap},
  author       = {Lasbordes, Maxence and Chatelain, Amélie and Seddah, Djamé},
  year         = {2026},
  eprint       = {2605.26735},
  archivePrefix= {arXiv},
  primaryClass = {cs.CL}
}