BFS-Prover: Scalable Best-First Tree Search for LLM-based Automatic Theorem Proving

Fuente: arXiv
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Main Authors: Xin, Ran, Xi, Chenguang, Yang, Jie, Chen, Feng, Wu, Hang, Xiao, Xia, Sun, Yifan, Zheng, Shen, Shen, Kai
Format: Preprint
Published: 2025
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author Xin, Ran
Xi, Chenguang
Yang, Jie
Chen, Feng
Wu, Hang
Xiao, Xia
Sun, Yifan
Zheng, Shen
Shen, Kai
author_facet Xin, Ran
Xi, Chenguang
Yang, Jie
Chen, Feng
Wu, Hang
Xiao, Xia
Sun, Yifan
Zheng, Shen
Shen, Kai
contents Recent advancements in large language models (LLMs) have spurred growing interest in automatic theorem proving using Lean4, where effective tree search methods are crucial for navigating the underlying large proof search spaces. While the existing approaches primarily rely on value functions and/or Monte Carlo Tree Search (MCTS), the potential of simpler methods like Best-First Tree Search (BFS) remains underexplored. In this paper, we investigate whether BFS can achieve competitive performance in large-scale theorem proving tasks. We present BFS-Prover, a scalable expert iteration framework, featuring three key innovations. First, we implement strategic data filtering at each expert iteration round, excluding problems solvable via beam search node expansion to focus on harder cases. Second, we improve the sample efficiency of BFS through Direct Preference Optimization (DPO) applied to state-tactic pairs automatically annotated with compiler error feedback, refining the LLM's policy to prioritize productive expansions. Third, we employ length normalization in BFS to encourage exploration of deeper proof paths. BFS-Prover achieves a state-of-the-art score of $72.95\%$ on the MiniF2F test set and therefore challenges the perceived necessity of complex tree search methods, demonstrating that BFS can achieve competitive performance when properly scaled. To facilitate further research and development in this area, we have open-sourced our model at https://huggingface.co/ByteDance-Seed/BFS-Prover-V1-7B.
format Preprint
id arxiv_https___arxiv_org_abs_2502_03438
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle BFS-Prover: Scalable Best-First Tree Search for LLM-based Automatic Theorem Proving
Xin, Ran
Xi, Chenguang
Yang, Jie
Chen, Feng
Wu, Hang
Xiao, Xia
Sun, Yifan
Zheng, Shen
Shen, Kai
Artificial Intelligence
Recent advancements in large language models (LLMs) have spurred growing interest in automatic theorem proving using Lean4, where effective tree search methods are crucial for navigating the underlying large proof search spaces. While the existing approaches primarily rely on value functions and/or Monte Carlo Tree Search (MCTS), the potential of simpler methods like Best-First Tree Search (BFS) remains underexplored. In this paper, we investigate whether BFS can achieve competitive performance in large-scale theorem proving tasks. We present BFS-Prover, a scalable expert iteration framework, featuring three key innovations. First, we implement strategic data filtering at each expert iteration round, excluding problems solvable via beam search node expansion to focus on harder cases. Second, we improve the sample efficiency of BFS through Direct Preference Optimization (DPO) applied to state-tactic pairs automatically annotated with compiler error feedback, refining the LLM's policy to prioritize productive expansions. Third, we employ length normalization in BFS to encourage exploration of deeper proof paths. BFS-Prover achieves a state-of-the-art score of $72.95\%$ on the MiniF2F test set and therefore challenges the perceived necessity of complex tree search methods, demonstrating that BFS can achieve competitive performance when properly scaled. To facilitate further research and development in this area, we have open-sourced our model at https://huggingface.co/ByteDance-Seed/BFS-Prover-V1-7B.
title BFS-Prover: Scalable Best-First Tree Search for LLM-based Automatic Theorem Proving
topic Artificial Intelligence
url https://arxiv.org/abs/2502.03438