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EPFL · CS-552 Modern NLP · spring 2025 · team of 4

STEM tutor

A small open-source model (0.6B parameters) that answers science multiple-choice questions like a tutor.

Qwen3-0.6B · SFT · DPO · QLoRA · RAG

The situation

baseQwen3-0.6BSFT24k questionsDPOpreferencesRAG62k documentsQLoRA0.5 GB

We built the data (24k STEM multiple-choice questions, preference triplets, 62k Wikipedia and arXiv documents), fine-tuned Qwen3-0.6B with SFT then DPO, added retrieval with a fine-tuned encoder, and quantised the model with QLoRA. The models and datasets are published on Hugging Face.

Results

accuracy after SFT
+4 %
with QLoRA, same accuracy
1.1 → 0.5 GB

CS-552 project, EPFL, 2025.

  • +4 % accuracy after SFT, and 73 % reward accuracy for the DPO model.
  • QLoRA 4-bit halves the model, from 1.1 to 0.5 GB, at equal accuracy.

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