A Probabilistic Framework for LLM Hallucination Detection via Belief Tree Propagation

Bairu Hou, Yang Zhang, Jacob Andreas, Shiyu Chang


Abstract
We describe Belief Tree Propagation (BTProp), a probabilistic framework for LLM hallucination detection. To judge the truth of a statement, BTProp generates a belief tree by recursively expanding the initial statement into a set of logically related claims, then reasoning globally about the relationships between these claims. BTProp works by constructing a probabilistic model of the LM itself: it reasons jointly about logical relationships between claims and relationships between claim probabilities and LM factuality judgments via probabilistic inference in a “hidden Markov tree”. This method improves over state-of-the-art baselines by 3%-9% (evaluated by AUROC and AUC-PR) on multiple hallucination detection benchmarks.
Anthology ID:
2025.naacl-long.158
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:
3076–3099
Language:
URL:
https://preview.aclanthology.org/moar-dois/2025.naacl-long.158/
DOI:
10.18653/v1/2025.naacl-long.158
Bibkey:
Cite (ACL):
Bairu Hou, Yang Zhang, Jacob Andreas, and Shiyu Chang. 2025. A Probabilistic Framework for LLM Hallucination Detection via Belief Tree Propagation. 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 3076–3099, Albuquerque, New Mexico. Association for Computational Linguistics.
Cite (Informal):
A Probabilistic Framework for LLM Hallucination Detection via Belief Tree Propagation (Hou et al., NAACL 2025)
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PDF:
https://preview.aclanthology.org/moar-dois/2025.naacl-long.158.pdf