InFi-Check: Interpretable and Fine-Grained Fact-Checking of LLMs on Grounding Documents

Yuzhuo Bai, Shuzheng Si, Kangyang Luo, Qingyi Wang, Wenhao Li, Gang Chen, Fanchao Qi, Maosong Sun


Abstract
Large language models (LLMs) often hallucinate, yet most existing fact-checking methods treat factuality evaluation as a binary classification problem, offering limited interpretability and failing to capture fine-grained error types. In this paper, we introduce InFi-Check, a framework for interpretable and fine-grained fact-checking of LLM outputs. Specifically, we first propose a controlled data synthesis pipeline that generates high-quality data featuring explicit evidence, fine-grained error type labels, justifications, and corrections. Based on this, we construct large-scale training data and a manually verified benchmark InFi-Check-FG for fine-grained fact-checking of LLM outputs. Building on these high-quality training data, we further propose InFi-Checker, which can jointly provide supporting evidence, classify fine-grained error types, and produce justifications along with corrections. Experiments show that InFi-Checker achieves state-of-the-art performance on InFi-Check-FG and strong generalization across various downstream tasks, significantly improving the utility and trustworthiness of factuality evaluation.
Anthology ID:
2026.emnlp-main.1136
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
26059–26087
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1136/
DOI:
Bibkey:
Cite (ACL):
Yuzhuo Bai, Shuzheng Si, Kangyang Luo, Qingyi Wang, Wenhao Li, Gang Chen, Fanchao Qi, and Maosong Sun. 2026. InFi-Check: Interpretable and Fine-Grained Fact-Checking of LLMs on Grounding Documents. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 26059–26087, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
InFi-Check: Interpretable and Fine-Grained Fact-Checking of LLMs on Grounding Documents (Bai et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1136.pdf