TreeThink: A Modular Tree Search Library for Mathematical Reasoning with LLMs

Burak Sina Akbudak, Zeynel Abidin Uluşan, Salih Can Erer, Gözde Gül Şahin


Abstract
Tree search algorithms enable systematic exploration of the proof space in neural theorem proving. Existing LLM tree search libraries primarily target natural language reasoning and do not provide native integration with formal verifiers, while theorem proving systems often rely on task-specific search implementations. We introduce TreeThink, an open-source Python library for modular, fully asynchronous tree search in neural theorem proving. It integrates established tree search methods with vLLM-based inference pipelines and diverse node evaluation techniques, ranging from lightweight heuristics to neural evaluators. We support Lean 4, Rocq, and Isabelle/HOL alongside natural language. It connects directly to each language’s Read-Eval-Print Loop (REPL) server for real-time verification and proof state extraction. We evaluate TreeThink on miniF2F and MATH500, demonstrating cross-language formal proof search, natural language reasoning support, and up to 8.0× wall-clock speedup from asynchronous execution. Source code is released under the MIT license at https://github.com/GGLAB-KU/treethink, and the library is accessible as a downloadable package at https://pypi.org/project/treethink/.
Anthology ID:
2026.emnlp-demos.57
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: System Demonstrations
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Sweta Agrawal, Alberto Abad
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
593–603
Language:
URL:
https://aclanthology.org/2026.emnlp-demos.57/
DOI:
Bibkey:
Cite (ACL):
Burak Sina Akbudak, Zeynel Abidin Uluşan, Salih Can Erer, and Gözde Gül Şahin. 2026. TreeThink: A Modular Tree Search Library for Mathematical Reasoning with LLMs. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: System Demonstrations, pages 593–603, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
TreeThink: A Modular Tree Search Library for Mathematical Reasoning with LLMs (Akbudak et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-demos.57.pdf