kunjcr2/qwen2.5-0.5b-sft-dpo

Qwen2.5-0.5B SFT + DPO (LoRA)

This repository contains:

• Merged SFT backbone trained on HuggingFaceH4/ultrachat_200k
• LoRA adapters fine-tuned with DPO using HuggingFaceH4/ultrafeedback_binarized

Both are packaged in one repo:

• Root = SFT backbone (full weights + tokenizer)
• dpo_adapters/ = LoRA adapters (DPO preference optimization)

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Model Details

• Developed by: Independent contributor
• Base model: Qwen/Qwen2.5-0.5B-Instruct
• Library: Transformers, PEFT, TRL
• Training type: Supervised fine-tuning (SFT) + Direct Preference Optimization (DPO)
• Languages: English (from UltraChat + UltraFeedback)
• License: Apache-2.0

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Uses

Direct Use

• Chat-style assistant
• Text generation, reasoning, and dialogue

Downstream Use

• Base for alignment research
• Further PEFT fine-tuning

Out-of-Scope

• High-stakes or safety-critical applications (e.g., medical, legal, political advice)

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Bias, Risks, and Limitations

• Biases present in the UltraChat and UltraFeedback datasets will carry over
• Model can generate hallucinated or unsafe outputs
• Should not be deployed without safety filtering

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How to Use

Pipeline only

# Use a pipeline as a high-level helper
from transformers import pipeline

pipe = pipeline("text-generation", model="kunjcr2/qwen2.5-0.5b-sft-dpo")
messages = [
    {"role": "user", "content": "Who are you?"},
]
pipe(messages)

With DPO adapters

from transformers import AutoTokenizer, AutoModelForCausalLM
from peft import PeftModel

tok = AutoTokenizer.from_pretrained("your-username/qwen2.5-0.5b-sft-dpo")
base = AutoModelForCausalLM.from_pretrained("your-username/qwen2.5-0.5b-sft-dpo", torch_dtype="auto", device_map="auto")
model = PeftModel.from_pretrained(base, "your-username/qwen2.5-0.5b-sft-dpo/dpo_adapters")

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Training Details

Data

• SFT: UltraChat (100k subset)
• DPO: UltraFeedback (binarized)

Hyperparameters

• SFT:

  • Epochs: 1
  • LR: 2e-5
  • Optimizer: AdamW
  • Batch size: 16 × 16 grad accumulation (effective 256)

• DPO:

  • Epochs: 1
  • LR: 1e-5
  • Beta: 0.1
  • LoRA rank: 8

Hardware

• Colab A100 / L4 (mixed bf16/TF32)
• Gradient checkpointing enabled

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Evaluation

• Qualitative: improved helpfulness and preference alignment over raw SFT
• Quantitative: not benchmarked yet (POC)

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Environmental Impact

• Hardware: single A100 (Colab Pro+)
• Runtime: ~few hours total (SFT + DPO)
• Emissions: not calculated

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Citation

If you use this model, cite Qwen as the base and this repo for the SFT+DPO adapters.

@misc{qwen2.5sftdpo,
  title = {Qwen2.5-0.5B SFT + DPO (LoRA)},
  author = {Your Name},
  year = {2025},
  publisher = {Hugging Face},
  howpublished = {\url{https://huggingface.co/kunjcr2/qwen2.5-0.5b-sft-dpo}}
}

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Framework Versions

• Transformers 4.x
• TRL latest
• PEFT 0.17.1

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