Using Probabilistic Programs to Train Inductive Reasoning in Large Language Models
使用概率程序训练大型语言模型的归纳推理
Liyi Zhang, Akshay K. Jagadish, Brenden M. Lake, Thomas L. Griffiths
AI总结 提出基于程序的后验训练(PPT)方法,利用LLM生成概率程序场景,通过推理产生分布目标,微调模型以提升归纳推理准确性、与人类判断的一致性及校准能力。
Comments 20 pages, 5 figures
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大型语言模型(LLM)的后训练推理通常专注于数学和编码等演绎任务,其中正确性可验证。然而,许多现实世界的推理问题是归纳性的:智能体必须从稀疏、模糊的观测中推断不确定的信念。使用标准微调方法进行归纳推理面临挑战,包括难以策划大规模、高质量标注数据集以及处理本质上是分布式的目标。在这项工作中,我们引入了一种称为基于程序的后验训练(PPT)的新方法来解决这些局限性:我们使用LLM生成多样化的开放世界场景作为概率程序,运行概率推理以产生查询的分布式目标响应,然后在这些概率软标签上进行微调。使用这种方法,我们在10,000个程序生成的场景上微调LLM,并在保留的模板、人工标注的判断和外部基准上进行评估。总体而言,PPT显著提高了保留归纳任务的估计准确性,增强了与人类判断的一致性,并迁移到估计和校准的外部基准。此外,原始校准的增益并未被事后温度缩放所涵盖,表明与输出重新缩放相比,模型更深入地内化了不确定性。这些结果表明,概率程序介导的微调是一种有前景的方法,用于后训练LLM以可靠地执行近似归纳推理。
Post-training Large Language Models (LLMs) for reasoning typically focuses on deductive tasks such as mathematics and coding where correctness is verifiable. Yet, many real-world reasoning problems are inductive: agents must infer uncertain beliefs from sparse, ambiguous observations. There are challenges to using standard fine-tuning methods for inductive reasoning, including difficulties in curating large-scale, high-quality labeled datasets and in handling targets that are inherently distributional. In this work, we introduce a novel approach, called Program-based Posterior Training (PPT), to address these limitations: we use an LLM to generate diverse open-world scenarios as probabilistic programs, run probabilistic inference to produce distributional target responses to queries, and then fine-tune on these probabilistic soft labels. Using this approach, we fine-tune LLMs on 10,000 programmatically generated scenarios and evaluate on held-out motifs, human-labeled judgments, and external benchmarks. Overall, PPT substantially improves estimation accuracy on held-out inductive tasks, increases alignment with human judgments, and transfers to external benchmarks for estimation and calibration. Additionally, the gains in raw calibration are not subsumed by post-hoc temperature scaling, showing that the models have more deeply internalized uncertainty compared to output rescaling. Together, these results suggest that probabilistic-program-mediated fine-tuning is a promising approach for post-training LLMs to reliably perform approximate inductive inference.