A longstanding goal in deep learning research has been to precisely characterize training and generalization. However, the often complex loss landscapes of neural networks have made a theory of learning dynamics elusive. In this work, we show that for wide neural networks the learning dynamics simplify considerably and that, in the infinite width limit, they are governed by a linear model obtained from the first-order Taylor expansion of the network around its initial parameters. Furthermore, mirroring the correspondence between wide Bayesian neural networks and Gaussian processes, gradient-based training of wide neural networks with a squared loss produces test set predictions drawn from a Gaussian process with a particular compositional kernel. While these theoretical results are only exact in the infinite width limit, we nevertheless find excellent empirical agreement between the predictions of the original network and those of the linearized version even for finite practically-sized networks. This agreement is robust across different architectures, optimization methods, and loss functions.

本文研究神经网络的学习和泛化性能，发现对于宽神经网络，学习动态变得简单，并且在无限宽度的极限下，它们由网络初始参数的一阶泰勒展开得到的线性模型控制。同时，通过在广义上拟合高斯过程的理论，揭示了神经网络可能表现出高斯过程的特性。

任意深度的宽神经网络在梯度下降下演化为线性模型