提出新算法提升概率电路参数学习效率与效果
Rethinking Probabilistic Circuit Parameter Learning
- 设计自适应学习率的批量EM算法,缓解小批次过拟合问题
- 在语言、图像、DNA数据上收敛更快且最终似然更高
- 适合大规模数据下的概率电路训练,尤其关注精度与速度
概率电路(PCs)为生成建模提供计算可扩展的框架,支持多种概率查询的精确高效推理。尽管近期进展显著提升了PC的表达能力和可扩展性,其参数的有效训练仍具挑战。现有广泛使用的全批量期望最大化(EM)方法需处理完整数据集才更新一次,对大数据集效率低下。虽然小批量经验扩展和基于梯度的方法收敛更快,但最终似然通常较差。我们通过建立这些实际算法与通用EM目标间的理论联系,揭示了根本问题:现有小批量EM和梯度方法未能正确正则化分布变化,导致每次更新实质上过拟合当前小批次。基于此洞察,我们提出anemone,一种新型小批量EM算法。anemone为每个参数应用隐式自适应学习率,按其对当前批次似然的贡献程度缩放。在语言、图像和DNA数据集上的大量实验表明,anemone在收敛速度和最终性能上均持续优于现有优化器。
原文摘要 · Abstract (English)
Probabilistic Circuits (PCs) offer a computationally scalable framework for generative modeling, supporting exact and efficient inference of a wide range of probabilistic queries. While recent advances have significantly improved the expressiveness and scalability of PCs, effectively training their parameters remains a challenge. In particular, a widely used optimization method, full-batch Expectation-Maximization (EM), requires processing the entire dataset before performing a single update, making it ineffective for large datasets. Although empirical extensions to the mini-batch setting, as well as gradient-based mini-batch algorithms, converge faster than full-batch EM, they generally underperform in terms of final likelihood. We investigate this gap by establishing a novel theoretical connection between these practical algorithms and the general EM objective. Our analysis reveals a fundamental issue that existing mini-batch EM and gradient-based methods fail to properly regularize distribution changes, causing each update to effectively ``overfit'' the current mini-batch. Motivated by this insight, we introduce anemone, a new mini-batch EM algorithm for PCs. Anemone applies an implicit adaptive learning rate to each parameter, scaled by how much it contributes to the likelihood of the current batch. Across extensive experiments on language, image, and DNA datasets, anemone consistently outperforms existing optimizers in both convergence speed and final performance.
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