---
library_name: transformers
tags: []
---

# Model Card for _Qwen2.5-0.5B-Instruct (Fine-Tuned on OpenR1-Math-220k, 2% Done, 50% underway Feb 13th)_

## Model Details

**Model Name**: Qwen2.5-0.5B-Instruct (GRPO Fine-Tuned)  
**Model ID**: `_Qwen2.5-0.5B-R1subset_`  
**License**: [Apache 2.0 / or whichever applies]  
**Finetuned From**: [Qwen/Qwen2.5-0.5B-Instruct](https://huggingface.co/Qwen/Qwen2.5-0.5B-Instruct)  
**Language(s)**: English (mathematical text)

**Developed By**: Christian H. Cooper
**Funding**: Self-sponsored  
**Shared By**: Christian H. Cooper  

### Model Description

This model is a **Qwen2.5-0.5B** base LLM fine-tuned on a **2% subset** of the [OpenR1-Math-220k](https://huggingface.co/datasets/open-r1/OpenR1-Math-220k) dataset. I used **Group Relative Policy Optimization (GRPO)** from the `trl` library, guiding the model toward producing well-formatted chain-of-thought answers in:

```
<reasoning>
  ...
</reasoning>
<answer>
  ...
</answer>
```

It focuses on math reasoning tasks, learning to generate a step-by-step solution (`<reasoning>`) and a numeric or final textual answer (`<answer>`). We incorporate reward functions that encourage correct chain-of-thought structure, numeric answers, and correctness.

### Model Sources
- **GitHub or Repo**: *[Pending]*  
- **Paper/Demo**: *[Pending]*

## Uses

### Direct Use
- **Math Problem Solving**: The model tries to reason through math word problems, providing step-by-step reasoning and a final answer.

### Downstream Use
- **Educational Tools**: Potentially used in tutoring or step-by-step solution generation.  
- **Math Chatbots**: A math helper that can respond in a structured `<reasoning>/<answer>` format.

### Out-of-Scope Use
- **High-Stakes Decisions**: Model is not guaranteed to be correct for advanced or critical math scenarios (finance, medical, engineering safety).  
- **Non-English**: Primary training data is English math text, so reliability in other languages is minimal.

## Bias, Risks, and Limitations

- **Bias**: Although this is a math-focused dataset, any language model can exhibit unintended biases.  
- **Risks**: The model may produce mathematically incorrect or incomplete solutions. The partial coverage (2% of the dataset) further limits accuracy.  
- **Limitations**: 
  - Only partially fine-tuned on 2% of the data, so correctness is not guaranteed.  
  - The chain-of-thought is for interpretability but may still contain flawed reasoning or leaps.

## How to Get Started

```python
from transformers import AutoTokenizer, AutoModelForCausalLM
import torch

model_name = "HarleyCooper/Qwen.5B-OpenR1Math"  # Will keep the same name through all % iterations. 
tokenizer = AutoTokenizer.from_pretrained(model_name)
model = AutoModelForCausalLM.from_pretrained(model_name).to("cuda")

prompt = """<reasoning>
Question: It is known that in a convex $n$-gon ($n>3$) no three diagonals pass through the same point.

Find the number of points (distinct from the vertices) of intersection of pairs of diagonals.
</reasoning>
<answer>
"""

inputs = tokenizer(prompt, return_tensors="pt").to("cuda")
outputs = model.generate(**inputs, max_new_tokens=2000)
answer = tokenizer.decode(outputs[0])
print(answer)
```

## Training Details

### Training Data

- **Dataset**: A 2% subsample (~4.4k problems) of [OpenR1-Math-220k](https://huggingface.co/datasets/open-r1/OpenR1-Math-220k).  
- **Data Format**: Each sample has `problem`, `solution`, `answer`. We transform them into:
  - `"prompt"`: A single string containing system instructions + the problem text.  
  - `"answer"`: A string with `<reasoning>` + `<answer>` blocks.

### Training Procedure

- **Framework**: [TRL (v0.4+)](https://github.com/lvwerra/trl) with Group Relative Policy Optimization (GRPO).  
- **Objective**: Reinforcement learning on chain-of-thought format, numeric correctness, and final-answer consistency.  
- **Reward Functions**:
  1. **`xmlcount_reward_func`**: Encourages `<reasoning>`/`<answer>` structure.  
  2. **`soft_format_reward_func`**: Checks for `<reasoning>.*</reasoning><answer>.*</answer>` in any multiline arrangement.  
  3. **`strict_format_reward_func`**: Strict multiline regex for exact formatting.  
  4. **`int_reward_func`**: Partial reward if the final `<answer>` is purely numeric.  
  5. **`correctness_reward_func`**: Binary reward if the final extracted answer exactly matches the known correct answer.

#### Training Hyperparameters

- **Base Model**: Qwen2.5-0.5B  
- **Learning Rate**: ~5e-6  
- **Batch Size**: 1–2 (due to GPU constraints)  
- **Optimizer**: AdamW (β1=0.9, β2=0.99)  
- **Scheduler**: Cosine with warmup_ratio=0.1  
- **Num Generations**: 16 (GRPO config)  
- **Number of Training Epochs**: 1 epoch on 2% data  
- **Hardware**: Single A100 40GB on Colab  
- **Max Prompt Length**: 256 tokens  
- **Max Completion Length**: 200 tokens  

### Speeds, Sizes, Times
- **Approx. Steps**: ~200–300 steps for 2% subset  
- **Run Time**: Varies from ~1 to 2 hours on Colab A100

## Evaluation

### Testing Data
- Currently trained + tested on the same subset (2%). Next step would be to evaluate on a withheld portion or the full set to measure true correctness.

### Metrics
- **Format Rewards**: `xmlcount`, `soft_format`, `strict_format`  
- **Correctness**: Exact match final numeric/string answer  
- **Partial Numeric**: `int_reward_func`

### Results
- The model shows a strong improvement in output format (70–80% format compliance) but relatively low exact numeric correctness. Additional epochs or a larger training fraction are needed for better correctness.

## Environmental Impact

- **Hardware**: Single A100 40GB GPU in a Colab environment  
- **Train Time**: ~1–2 hours on 2% data  
- **Carbon Footprint**: Not measured exactly, but minimal compared to large-scale runs

## Model Architecture & Objective

- **Architecture**: Transformer-based causal language model (Qwen2.5-0.5B)  
- **Objective**: RL-based chain-of-thought generation for math reasoning

## Citation

```
@misc{cooperQwen2.5-0.5B,
  title={Qwen2.5-0.5B Fine-Tuned on OpenR1 (2% subset)},
  author={Christian H. Cooper.},
  howpublished={\url{https://huggingface.co/Christian-cooper-us/Qwen2.5-0.5B-R1subset}},
  year={2025},
}
```

## Contact
- Maintainers: Christian Cooper (GitHub: [@christian-cooper-us](https://huggingface.co/HarleyCooper)), others.

---

**Disclaimer**: This model is experimental, trained on only 2% of the dataset. It may produce inaccurate math solutions and is not suitable for high-stakes or time-sensitive deployments.