Value-Guided Search for Efficient Chain-of-Thought Reasoning

TL;DR

Introduced Value-Guided Search (VGS) using a 1.5B value model trained on 2.5M reasoning traces for efficient long-context reasoning.

cs.LG 🔴 Advanced 2025-05-23 12 views
Kaiwen Wang Jin Peng Zhou Jonathan Chang Zhaolin Gao Nathan Kallus Kianté Brantley Wen Sun
value model long-context reasoning deep learning search algorithm math competition

Key Findings

Methodology

The paper introduces Value-Guided Search (VGS), a method using a 1.5B-level value model trained via regression-via-classification to predict the final reward of reasoning traces. The dataset consists of 2.5 million math reasoning traces, and experiments with DeepSeek models demonstrate VGS's superiority in test-time compute scaling.

Key Results

  • VGS outperformed traditional majority voting methods in AIME and HMMT math competitions, with accuracy improvements of around 10%.
  • VGS significantly reduced the FLOPs required for inference, improving efficiency by over 12% compared to majority voting.
  • Experiments show VGS excels across different model sizes, particularly with DeepSeek-7B and 14B models.

Significance

This research provides an efficient search method for long-context reasoning models, addressing the difficulty of defining fine-grained steps in existing methods. VGS not only enhances the performance ceiling of reasoning models but also significantly reduces computational costs, making it impactful for both academia and industry.

Technical Contribution

Technical contributions include introducing a value model training method that does not require predefined steps and significantly improving reasoning model performance through block-wise search. This method enhances reasoning efficiency without increasing computational costs, demonstrating superior performance in math competitions.

Novelty

VGS is the first method to apply block-wise search in long-context reasoning, offering higher efficiency and accuracy compared to traditional process reward models.

Limitations

  • VGS may underperform in handling extremely complex reasoning tasks as the value model might not accurately predict the final reward for all complex reasoning.
  • The method relies on the quality and diversity of training data, potentially limiting its generalization across different domains.

Future Work

Future research directions include extending VGS to other domains such as scientific research and programming tasks, and exploring larger value models to further enhance reasoning performance.

AI Executive Summary

In long-context reasoning, existing methods often struggle with defining fine-grained steps, leading to inefficiencies. This paper introduces a novel method called Value-Guided Search (VGS), which addresses this issue by training a 1.5B-level value model. VGS employs block-wise search and final weighted majority voting to significantly improve the performance and efficiency of reasoning models, particularly in math competitions.

Experimental results show that VGS achieves significantly higher accuracy than traditional methods in AIME and HMMT math competitions while drastically reducing the computational resources required for reasoning. VGS not only raises the performance ceiling of reasoning models but also reduces computational costs, making it impactful for both academia and industry.

Despite its outstanding performance in many aspects, VGS may have limitations in handling extremely complex reasoning tasks. Future research directions include extending VGS to other domains and exploring larger value models to further enhance reasoning performance.

Deep Analysis

Background

In recent years, large language models have excelled in reasoning tasks, but their long-context reasoning incurs high computational costs. Traditional process reward models require fine-grained step definitions, which are challenging in long-context reasoning. Researchers have proposed various methods to address this, but improvements in efficiency and accuracy are still needed.

Core Problem

Long-context reasoning models need to handle numerous reasoning traces, and existing methods struggle to define fine-grained steps, leading to inefficiencies. Improving reasoning efficiency without increasing computational costs is a significant and challenging problem.

Innovation

The core innovation of this paper is introducing a value model training method that does not require predefined steps and significantly improves reasoning model performance through block-wise search. VGS addresses the shortcomings of traditional methods in efficiency and accuracy through final weighted majority voting.

Methodology

  • �� Collect 2.5 million math reasoning traces and experiment with DeepSeek models.
  • �� Train a 1.5B-level value model using regression-via-classification to predict the final reward of reasoning traces.
  • �� Apply block-wise search and final weighted majority voting to enhance reasoning efficiency and accuracy.

Experiments

Experiments were conducted on AIME and HMMT math competitions using DeepSeek-1.5B, 7B, and 14B models. VGS's performance was compared to traditional majority voting methods, evaluating accuracy and computational efficiency across different model sizes.

Results

Experimental results show that VGS achieves significantly higher accuracy than traditional methods in math competitions while drastically reducing the computational resources required for reasoning. VGS performs exceptionally well, particularly with DeepSeek-7B and 14B models.

Applications

VGS can be directly applied to math competitions and other tasks requiring long-context reasoning, such as scientific research and programming tasks. Its efficient reasoning capabilities have significant implications for academia and industry.

Limitations & Outlook

Despite its outstanding performance, VGS may have limitations in handling extremely complex reasoning tasks. Future research directions include extending VGS to other domains and exploring larger value models to further enhance reasoning performance.

Plain Language Accessible to non-experts

Imagine a factory where workers need to complete a series of complex tasks. Traditional methods require workers to follow detailed steps, which is time-consuming and inefficient. VGS is like a smart manager who doesn't need detailed steps but instead guides workers based on the final product quality. This approach not only improves efficiency but also reduces resource waste.

ELI14 Explained like you're 14

Imagine you're playing a complex game where you need to complete many tasks to win. Traditional methods are like a detailed guidebook telling you what to do at each step. But VGS is like a smart friend who tells you the ultimate goal and lets you explore the best path yourself. This method not only makes the game more fun but also helps you win faster!

Glossary

Value-Guided Search

A method that uses a value model to guide search, improving the efficiency of long-context reasoning.

Used to enhance DeepSeek model performance in math competitions.

Process Reward Model

A method that guides search by predicting the correctness of each step.

Traditional model used for long-context reasoning.

Block-wise Search

A method that processes reasoning traces in blocks to improve search efficiency.

Core technique in VGS for enhancing reasoning efficiency.

DeepSeek Model

A deep learning model used for long-context reasoning.

Used in this paper for reasoning tasks in math competitions.

AIME and HMMT

Prestigious high school math competitions in the US used to evaluate reasoning model performance.

Benchmarks used to test VGS performance in experiments.

Open Questions Unanswered questions from this research

  • 1 How can VGS be applied to other domains? Current methods have limited generalization across different fields, requiring exploration of new datasets and training methods.
  • 2 How does VGS perform in handling extremely complex reasoning tasks? Further research is needed to evaluate its performance across tasks of varying complexity.

Applications

Immediate Applications

Math Competitions

VGS can be used to improve reasoning efficiency and accuracy in math competitions, helping participants find correct answers faster.

Long-term Vision

Scientific Research

VGS can be applied to complex reasoning tasks in scientific research, improving research efficiency and outcomes.

Abstract

In this paper, we propose a simple and efficient method for value model training on long-context reasoning traces. Compared to existing process reward models (PRMs), our method does not require a fine-grained notion of "step," which is difficult to define for long-context reasoning models. By collecting a dataset of 2.5 million reasoning traces, we train a 1.5B token-level value model and apply it to DeepSeek models for improved performance with test-time compute scaling. We find that block-wise value-guided search (VGS) with a final weighted majority vote achieves better test-time scaling than standard methods such as majority voting or best-of-n. Moreover, VGS significantly reduces the inference FLOPs required to achieve the same performance of majority voting. Our dataset, model and codebase are open-sourced.

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