Learning to Reason for Factuality

Fuente: arXiv
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Main Authors: Chen, Xilun, Kulikov, Ilia, Berges, Vincent-Pierre, Oğuz, Barlas, Shao, Rulin, Ghosh, Gargi, Weston, Jason, Yih, Wen-tau
Format: Preprint
Published: 2025
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author Chen, Xilun
Kulikov, Ilia
Berges, Vincent-Pierre
Oğuz, Barlas
Shao, Rulin
Ghosh, Gargi
Weston, Jason
Yih, Wen-tau
author_facet Chen, Xilun
Kulikov, Ilia
Berges, Vincent-Pierre
Oğuz, Barlas
Shao, Rulin
Ghosh, Gargi
Weston, Jason
Yih, Wen-tau
contents Reasoning Large Language Models (R-LLMs) have significantly advanced complex reasoning tasks but often struggle with factuality, generating substantially more hallucinations than their non-reasoning counterparts on long-form factuality benchmarks. However, extending online Reinforcement Learning (RL), a key component in recent R-LLM advancements, to the long-form factuality setting poses several unique challenges due to the lack of reliable verification methods. Previous work has utilized automatic factuality evaluation frameworks such as FActScore to curate preference data in the offline RL setting, yet we find that directly leveraging such methods as the reward in online RL leads to reward hacking in multiple ways, such as producing less detailed or relevant responses. We propose a novel reward function that simultaneously considers the factual precision, response detail level, and answer relevance, and applies online RL to learn high quality factual reasoning. Evaluated on six long-form factuality benchmarks, our factual reasoning model achieves an average reduction of 23.1 percentage points in hallucination rate, a 23% increase in answer detail level, and no degradation in the overall response helpfulness.
format Preprint
id arxiv_https___arxiv_org_abs_2508_05618
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Learning to Reason for Factuality
Chen, Xilun
Kulikov, Ilia
Berges, Vincent-Pierre
Oğuz, Barlas
Shao, Rulin
Ghosh, Gargi
Weston, Jason
Yih, Wen-tau
Computation and Language
Reasoning Large Language Models (R-LLMs) have significantly advanced complex reasoning tasks but often struggle with factuality, generating substantially more hallucinations than their non-reasoning counterparts on long-form factuality benchmarks. However, extending online Reinforcement Learning (RL), a key component in recent R-LLM advancements, to the long-form factuality setting poses several unique challenges due to the lack of reliable verification methods. Previous work has utilized automatic factuality evaluation frameworks such as FActScore to curate preference data in the offline RL setting, yet we find that directly leveraging such methods as the reward in online RL leads to reward hacking in multiple ways, such as producing less detailed or relevant responses. We propose a novel reward function that simultaneously considers the factual precision, response detail level, and answer relevance, and applies online RL to learn high quality factual reasoning. Evaluated on six long-form factuality benchmarks, our factual reasoning model achieves an average reduction of 23.1 percentage points in hallucination rate, a 23% increase in answer detail level, and no degradation in the overall response helpfulness.
title Learning to Reason for Factuality
topic Computation and Language
url https://arxiv.org/abs/2508.05618