论文标题
域调整后的回归或:ERM可能已经学习足以用于分布概括的功能
Domain-Adjusted Regression or: ERM May Already Learn Features Sufficient for Out-of-Distribution Generalization
论文作者
论文摘要
对于深网概括过分分发的一个常见解释是,它们无法恢复“正确”的功能。我们通过一个简单的实验挑战了这个概念,该实验表明ERM已经学习了足够的特征,并且当前的瓶颈不是特征学习,而是稳健的回归。我们的发现还表明,鉴于目标分布的少量数据,仅重新训练最后一个线性层将带来出色的性能。因此,我们认为,设计更简单的方法来学习对现有特征的预测因素是未来研究的有希望的方向。为此,我们介绍了域调整后的回归(DARE),这是学习线性预测变量的凸目标,在新的分布变化模型下,该线性预测变量可证明是可靠的。 Duare没有学习一个功能,而是执行特定于域的调整,以在规范的潜在空间中统一域,并学会在此空间中预测。在自然模型下,我们证明了DARE解决方案是一组受约束的测试分布集的最小值预测指标。此外,我们为最小值风险提供了第一个有限环境的融合保证,从而改善了现有的分析,这些分析仅在环境阈值后产生最小值预测变量。根据鉴定功能进行了评估,我们发现敢于与先前的方法相比,始终达到相等或更好的性能。
A common explanation for the failure of deep networks to generalize out-of-distribution is that they fail to recover the "correct" features. We challenge this notion with a simple experiment which suggests that ERM already learns sufficient features and that the current bottleneck is not feature learning, but robust regression. Our findings also imply that given a small amount of data from the target distribution, retraining only the last linear layer will give excellent performance. We therefore argue that devising simpler methods for learning predictors on existing features is a promising direction for future research. Towards this end, we introduce Domain-Adjusted Regression (DARE), a convex objective for learning a linear predictor that is provably robust under a new model of distribution shift. Rather than learning one function, DARE performs a domain-specific adjustment to unify the domains in a canonical latent space and learns to predict in this space. Under a natural model, we prove that the DARE solution is the minimax-optimal predictor for a constrained set of test distributions. Further, we provide the first finite-environment convergence guarantee to the minimax risk, improving over existing analyses which only yield minimax predictors after an environment threshold. Evaluated on finetuned features, we find that DARE compares favorably to prior methods, consistently achieving equal or better performance.