Reward-Guided Tree Search for Inference Time Alignment of Large Language Models

Chia-Yu Hung, Navonil Majumder, Ambuj Mehrish, Soujanya Poria


Abstract
Inference-time computation methods enhance the performance of Large Language Models (LLMs) by leveraging additional computational resources to achieve superior results. Common techniques, such as Best-of-N sampling, Majority Voting, and variants of tree-search algorithm have proven to be effective in boosting the performance of LLMs. These approaches strategically trade increased computational resource for improved model responses. In this work, we proposed DARWIN, an inference-time alignment method that leverage the guidance of a reward model to achieve alignment through reward-guided tree search. Empirical evidences indicates that our method outperform other inference-time alignment methods such as Best-of-N and ARGS on two widely accepted alignment benchmarks AlpacaEval 2 and MT-Bench. Furthermore, we show that our inference-time approach achieves performance comparable to preference-tuned models on both benchmarks, highlighting the effectiveness of trading inference-time compute for enhanced performance during inference.
Anthology ID:
2025.naacl-long.625
Volume:
Proceedings of the 2025 Conference of the Nations of the Americas Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers)
Month:
April
Year:
2025
Address:
Albuquerque, New Mexico
Editors:
Luis Chiruzzo, Alan Ritter, Lu Wang
Venue:
NAACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
12575–12593
Language:
URL:
https://preview.aclanthology.org/fix-sig-urls/2025.naacl-long.625/
DOI:
Bibkey:
Cite (ACL):
Chia-Yu Hung, Navonil Majumder, Ambuj Mehrish, and Soujanya Poria. 2025. Reward-Guided Tree Search for Inference Time Alignment of Large Language Models. In Proceedings of the 2025 Conference of the Nations of the Americas Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers), pages 12575–12593, Albuquerque, New Mexico. Association for Computational Linguistics.
Cite (Informal):
Reward-Guided Tree Search for Inference Time Alignment of Large Language Models (Hung et al., NAACL 2025)
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PDF:
https://preview.aclanthology.org/fix-sig-urls/2025.naacl-long.625.pdf