Unifying Tree Search Algorithm and Reward Design for LLM Reasoning: A Survey

Jiaqi Wei; Xiang Zhang; Yuejin Yang; Wenxuan Huang; Juntai Cao; Sheng Xu; Xiang Zhuang; Zhangyang Gao; Muhammad Abdul-Mageed; Laks V. S. Lakshmanan; Chenyu You; Wanli Ouyang; Siqi Sun

arXiv · 2510.09988

Unifying Tree Search Algorithm and Reward Design for LLM Reasoning: A Survey

Jiaqi Wei·Xiang Zhang·Yuejin Yang·Wenxuan Huang·Juntai Cao·Sheng Xu·Xiang Zhuang·Zhangyang Gao·Muhammad Abdul-Mageed·Laks V. S. Lakshmanan·Chenyu You·Wanli Ouyang·Siqi Sun

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Abstract

Deliberative tree search is a cornerstone of modern Large Language Model (LLM) research, driving the pivot from brute-force scaling toward algorithmic efficiency. This single paradigm unifies two critical frontiers: \textbf{Test-Time Scaling (TTS)}, which deploys on-demand computation to solve hard problems, and \textbf{Self-Improvement}, which uses search-generated data to durably enhance model parameters. However, this burgeoning field is fragmented and lacks a common formalism, particularly concerning the ambiguous role of the reward signal -- is it a transient heuristic or a durable learning target? This paper resolves this ambiguity by introducing a unified framework that deconstructs search algorithms into three core components: the \emph{Search Mechanism}, \emph{Reward Formulation}, and \emph{Transition Function}. We establish a formal distinction between transient \textbf{Search Guidance} for TTS and durable \textbf{Parametric Reward Modeling} for Self-Improvement. Building on this formalism, we introduce a component-centric taxonomy, synthesize the state-of-the-art, and chart a research roadmap toward more systematic progress in creating autonomous, self-improving agents.

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Jiaqi Wei, Xiang Zhang, Yuejin Yang, Wenxuan Huang, Juntai Cao, Sheng Xu, Xiang Zhuang, Zhangyang Gao, Muhammad Abdul-Mageed, Laks V. S. Lakshmanan, Chenyu You, Wanli Ouyang, Siqi Sun. 2025-10-11. Unifying Tree Search Algorithm and Reward Design for LLM Reasoning: A Survey. https://arxiv.org/abs/2510.09988

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