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arXiv 2406.10099cs.CL
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知晓未知:一种面向LLM指令微调的不确定性敏感方法

Know the Unknown: An Uncertainty-Sensitive Method for LLM Instruction Tuning

The Hong Kong University of Science and Technology(香港科学与技术大学)

Jiaqi Li, Yixuan Tang, Yi Yang

AI总结:

针对LLM难以承认知识局限的问题,提出不确定性敏感的两阶段微调方法US-Tuning,增强知识边界识别与指令遵循,显著减少幻觉,并在Llama2-7B上超越GPT-4。

摘要:

大型语言模型(LLMs)展示了卓越的能力,但也面临幻觉带来的挑战,这些幻觉通常源于知识或上下文的不足。尽管通过让LLM回答“我不知道”来指示其承认知识局限似乎很有前景,但我们发现模型始终难以承认知识空白。这一挑战可能源于当前的指令数据集强调答案生成而非知识边界意识。为解决这一局限,我们引入了不确定性与敏感性感知微调(US-Tuning),一种新颖的两阶段方法,用于上下文问答(QA)。第一阶段增强LLM识别其知识边界的能力,而第二阶段通过精心设计的因果提示强化指令遵循。我们的实验结果表明,US-Tuning不仅显著减少了上下文问答中的错误答案,还提高了模型对其参数化知识的忠实度,从而缓解了通用问答任务中的幻觉。我们微调的Llama2-7B模型在处理超出知识范围的问题上实现了高达34.7%的提升,并且在整体性能上比GPT-4高出4.2%。

英文摘要:

Large language models (LLMs) demonstrate remarkable capabilities but face challenges from hallucinations, which typically arise from insufficient knowledge or context. While instructing LLMs to acknowledge knowledge limitations by responding with "I don't know" appears promising, we find that models consistently struggle with admitting knowledge gaps. This challenge may originate from current instruction datasets that emphasise answer generation over knowledge boundary awareness. To address this limitation, we introduce Uncertainty-and-Sensitivity-Aware Tuning (US-Tuning), a novel two-stage approach for contextual question answering (QA). The first stage enhances LLMs' ability to recognise their knowledge boundaries, while the second stage reinforces instruction adherence through carefully designed causal prompts. Our experimental results demonstrate that US-Tuning not only significantly reduces incorrect answers in contextual QA but also improves models' faithfulness to their parametric knowledge, mitigating hallucinations in general QA tasks. Our fine-tuned Llama2-7B model achieves up to a 34.7% improvement in handling out-of-knowledge questions and outperforms GPT-4 by 4.2% in overall performance.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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