An open question in the Deep Learning community is why neural networks trained with Gradient Descent generalize well on real datasets even though they are capable of fitting random data. We propose an approach to answering this question based on a hypothesis about the dynamics of gradient descent that we call Coherent Gradients: Gradients from similar examples are similar and so the overall gradient is stronger in certain directions where these reinforce each other. Thus changes to the network parameters during training are biased towards those that (locally) simultaneously benefit many examples when such similarity exists. We support this hypothesis with heuristic arguments and perturbative experiments and outline how this can explain several common empirical observations about Deep Learning. Furthermore, our analysis is not just descriptive, but prescriptive. It suggests a natural modification to gradient descent that can greatly reduce overfitting.

本文提出了一个关于如何解释神经网络使用梯度下降算法泛化能力较强的假设Coherent Gradients，并支持该假设的启发式论证和简单实验证明。同时，该分析为防止过拟合提出了一种自然而然的梯度下降修改方法。

相干梯度: 一种理解基于梯度下降的优化中泛化性质的方法