Value-Guided Search for Efficient Chain-of-Thought Reasoning
Authors: name: Kaiwen Wang, name: Jin Peng Zhou, name: Jonathan Chang, name: Zhaolin Gao, name: Nathan Kallus, name: Kianté Brantley, name: Wen Sun

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. With an inference budget of 64
generations, VGS with DeepSeek-R1-Distill-1.5B achieves an average accuracy of
45.7% across four competition math benchmarks (AIME 2024 & 2025, HMMT Feb 2024
& 2025), reaching parity with o3-mini-medium. Moreover, VGS significantly
reduces the inference FLOPs required to achieve the same performance of
majority voting. Our dataset, model and codebase are open-sourced.