+

Research on AI

Stop Summation: Min-Form Credit Assignment Is All Process Reward Model Needs for Reasoning

Papers with Code Papers with Code
Reporter Naomi Wilson

By Naomi Wilson

Posted on: April 23, 2025

Stop Summation: Min-Form Credit Assignment Is All Process Reward Model Needs for Reasoning

**Analysis of the Research Paper**

The research paper "Stop Summation: Min-Form Credit Assignment Is All Process Reward Model Needs for Reasoning" proposes a novel method called PURE (Process sUpervised Reinforcement lEarning) to address the issue of reward hacking in process reward models (PRMs). PRMs have been shown to be effective for scaling large language models on challenging reasoning tasks, but they are limited by their susceptibility to reward hacking.

**What is the paper trying to achieve?**

The authors aim to alleviate the problem of reward hacking in PRMs by introducing a new credit assignment method called min-form. This method formulates the value function as the minimum of future rewards, rather than the cumulative sum of gamma-decayed future rewards used in traditional PRMs.

**Potential use cases:**

1. **Improving reasoning performance**: By using PURE, researchers and practitioners can develop more robust process reward models that are less prone to reward hacking.

2. **Fine-tuning large language models**: The paper demonstrates the effectiveness of PURE in fine-tuning large language models on challenging reasoning tasks, achieving comparable performance to verifiable reward-based methods within fewer steps.

**Significance in the field of AI:**

1. **Advancements in reinforcement learning**: PURE contributes to the development of more efficient and effective credit assignment methods for reinforcement learning, a crucial component of many AI applications.

2. **Improved robustness**: The paper highlights the importance of addressing reward hacking issues in PRMs, which can lead to overfitting and poor generalization.

**Papers with Code post:**

You can access the code and models related to this research on GitHub at [https://github.com/CJReinforce/PURE](https://github.com/CJReinforce/PURE).

**Conclusion:**

The paper proposes a novel method called PURE, which uses min-form credit assignment to alleviate reward hacking in process reward models. The results demonstrate the effectiveness of PURE in improving reasoning performance and fine-tuning large language models on challenging tasks. This work contributes significantly to the field of reinforcement learning and AI research.

Please note that you can access the paper directly through the provided link: https://paperswithcode.com/paper/stop-summation-min-form-credit-assignment-is