ASE-MCTS: Asynchronous Self-Evaluated Monte Carlo Tree Search for Efficient LLM Reasoning

Yang Wu, Yuyang Liu, Zhicheng Zhang, Xiaolong Zheng


Abstract
Monte Carlo Tree Search (MCTS) is a promising test-time method for improving LLMs on hard reasoning problems, where correct trajectories are often sparse. Self-evaluated MCTS is attractive because it avoids external reward models, verifiers, and stronger judges, but it faces a central paradox: MCTS depends on reliable intermediate rewards, while LLM self-evaluation is noisy and unstable. We propose ASE-MCTS, an Asynchronous Self-Evaluated MCTS framework. ASE-MCTS uses search-oriented reward analysis to derive an effective composition of rollout, process, and pairwise rewards from their global and local search roles. It further combines flexible search-space control with dependency-aware asynchronous execution, reducing redundant exploration and latency. Experiments on mathematical and scientific reasoning benchmarks show that ASE-MCTS improves reasoning without external supervision, especially on hard sparse-trajectory problems, and achieves up to a 6× wall-clock speedup over Sync-MCTS in the branch-factor scalability experiment.
Anthology ID:
2026.findings-emnlp.973
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
20572–20591
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.973/
DOI:
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Cite (ACL):
Yang Wu, Yuyang Liu, Zhicheng Zhang, and Xiaolong Zheng. 2026. ASE-MCTS: Asynchronous Self-Evaluated Monte Carlo Tree Search for Efficient LLM Reasoning. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 20572–20591, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
ASE-MCTS: Asynchronous Self-Evaluated Monte Carlo Tree Search for Efficient LLM Reasoning (Wu et al., Findings 2026)
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https://aclanthology.org/2026.findings-emnlp.973.pdf