---
language:
  - en
  - zh
license: apache-2.0
library_name: transformers
pipeline_tag: text-generation
tags:
  - qwen3
  - causal-lm
  - supervised-fine-tuning
  - math
  - reasoning
  - code
  - science
base_model: Qwen/Qwen3-4B-Base
model-index:
  - name: Qwen3-4B-SFT
    results:
      - task:
          type: text-generation
        dataset:
          name: AIME 2024
          type: aime2024
        metrics:
          - name: accuracy
            type: accuracy
            value: 20.8
      - task:
          type: text-generation
        dataset:
          name: AIME 2025
          type: aime2025
        metrics:
          - name: accuracy
            type: accuracy
            value: 19.4
      - task:
          type: text-generation
        dataset:
          name: AMC 2023
          type: amc2023
        metrics:
          - name: accuracy
            type: accuracy
            value: 58.0
      - task:
          type: text-generation
        dataset:
          name: GPQA-Diamond
          type: gpqa_diamond
        metrics:
          - name: accuracy
            type: accuracy
            value: 29.1
---

## Qwen3-4B-SFT:

Qwen3-4B-SFT is a reasoning-focused model derived from Qwen3-4B-Base via full-parameter fine-tuning on the verl framework. 

There is a notable shortage of reproducible 'warm-start' SFT bases in open-source practice, this model bridges the gap between base models and reinforcement learning models. Optimally aligned for Chain-of-Thought (CoT) and instruction following, it serves as a robust warm-start for Reinforcement Learning.

| Dataset | Base (4B)† | Qwen3-4B-SFT (this model) | Improvement |
| :--- | :---: | :---: | :---: |
| **AIME 2024** | 11.25% | **20.8%** | +9.55% |
| **AIME 2025** | 6.46% | **19.4%** | +12.94% |
| **AMC 2023** | 31.09% | **58.0%** | +26.91% |
| **GPQA-Diamond** | 7.77% | **29.1%** | +21.33% |

† Base (4B) figures are taken from [ (arXiv:2602.10885)](https://arxiv.org/pdf/2602.10885).

- Dataset card used for SFT: https://huggingface.co/datasets/96kevinli29/SFT-Dataset

## Qwen3-style reasoning and instruction following

Minimal pattern (illustrative):

```text
<|im_start|>user
… Among options A–D, which is correct? Reason step by step and put the final letter in \boxed{}.
<|im_end|>

<|im_start|>assistant
<think>
Compare A vs B vs C vs D against the stem; eliminate …; D remains consistent with …
</think>
Step-by-step: … (short derivation in the visible channel)
Final answer: \boxed{D}
<|im_end|>
```
Use a large enough **`max_new_tokens`** on hard math so both the **reasoning block** and the **visible** `\boxed{…}` line fit before generation stops.

## Configuration Notes

- Template: Trained with the **Qwen chat template**; learns to end responses with `<|im_end|>` (151645).
- Suggested Configuration:
  ```json
  {
    "eos_token_id": 151645
  }
  ```
You may adjust settings according to your training or deployment needs.

## Training Infrastructure

- Cluster: MeluXina Supercomputer (LuxProvide)
- Node Config: 4 NVIDIA-A100 GPUs per node.
- Final SFT Run: 12 Node-hours (16× A100 for 3 hours)
- Total R&D Investment: ~700 Node-hours (Includes data ablation, hyperparameter sweeps, and extensive benchmark evaluation.)

## Project Links

- Training code repository: https://github.com/96kevinli29/base-model-sft-verl

## Limitations

- Not optimized for factual correctness in all domains
- May still produce hallucinations or unsafe outputs
- Performance is sensitive to prompt style and decoding settings

## Citation

If you use this model, please cite **this checkpoint**, bibTeX for this release :

```bibtex
@misc{qwen3-4b-sft-2026,
  title        = {{Qwen3-4B-SFT}: Supervised Fine-Tuned {Qwen3}-4B for Reasoning},
  author       = {Hongyang Li, Xiao Li and {Sea-Fill Community}},
  year         = {2026},
  publisher    = {Hugging Face},
  howpublished = {\url{https://huggingface.co/SeaFill2025/Qwen3-4B-SFT}},
  note         = {Checkpoint trained with verl; warm-start for pre-RL alignment research. Maintained by Sea-Fill Community.}
}
```