论文标题

在线学习因果模型

Learning Causal Models Online

论文作者

Javed, Khurram, White, Martha, Bengio, Yoshua

论文摘要

预测模型 - 从不涵盖完整数据分布的观察数据中学到的 - 可以依靠数据中的虚假相关性来做出预测。这些相关性使模型变脆并阻碍概括。实现强烈概括的一种解决方案是将因果结构纳入模型。这种结构通过忽略与它们相矛盾的相关性来限制学习。但是,学习这些结构本身就是一个棘手的问题。此外,尚不清楚如何将因果关系的机制与在线持续学习结合在一起。在这项工作中,我们采用一种间接方法来发现因果模型。我们没有直接搜索真正的因果模型,而是提出了一种在线算法,该算法不断检测和消除虚假功能。我们的算法涉及这样的想法,即虚假特征与目标的相关性并非持续不断。结果,与该功能相关的重量正在不断变化。我们表明,通过不断删除此类特征,我们的方法会收敛到具有强烈概括的解决方案。此外,我们的方法与随机搜索相结合还可以从原始感觉数据中发现非毛发性特征。最后,我们的工作强调,问题的时间结构中存在的信息(通过整理数据破坏)对于在线检测虚假功能至关重要。

Predictive models -- learned from observational data not covering the complete data distribution -- can rely on spurious correlations in the data for making predictions. These correlations make the models brittle and hinder generalization. One solution for achieving strong generalization is to incorporate causal structures in the models; such structures constrain learning by ignoring correlations that contradict them. However, learning these structures is a hard problem in itself. Moreover, it's not clear how to incorporate the machinery of causality with online continual learning. In this work, we take an indirect approach to discovering causal models. Instead of searching for the true causal model directly, we propose an online algorithm that continually detects and removes spurious features. Our algorithm works on the idea that the correlation of a spurious feature with a target is not constant over-time. As a result, the weight associated with that feature is constantly changing. We show that by continually removing such features, our method converges to solutions that have strong generalization. Moreover, our method combined with random search can also discover non-spurious features from raw sensory data. Finally, our work highlights that the information present in the temporal structure of the problem -- destroyed by shuffling the data -- is essential for detecting spurious features online.

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