arXiv AI By Jiawei Dong, Zilong Bai, Pengtian zhu, Peng Zhou

SOPO: Socratic Guided Policy Optimization for Span-Level Hallucination Detection

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SOPO: Socratic Guided Policy Optimization for Span-Level Hallucination Detection introduces a multi-turn reinforcement learning framework that uses a teacher model to provide Socratic feedback, guiding reasoning trajectories during rollout. This approach addresses localization ambiguity, reward sparsity, and verbosity bias in detecting hallucinations in large language models. Empirical results on the RAGTruth dataset show that SOPO (4B) outperforms leading proprietary models and standard RL baselines, achieving state‑of‑the‑art performance on multiple benchmarks.

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