We study the expressivity of deep neural networks with random weights. We provide several results, both theoretical and experimental, precisely characterizing their functional properties in terms of the depth and width of the network. In doing so, we illustrate inherent connections between the length of a latent trajectory, local neuron transitions, and network activation patterns. The latter, a notion defined in this paper, is further studied using properties of hyperplane arrangements, which also help precisely characterize the effect of the neural network on the input space. We further show dualities between changes to the latent state and changes to the network weights, and between the number of achievable activation patterns and the number of achievable labellings over input data. We see that the depth of the network affects all of these quantities exponentially, while the width appears at most as a base. These results also suggest that the remaining depth of a neural network is an important determinant of expressivity, supported by experiments on MNIST and CIFAR-10.

本文提出了一种新的神经网络表达性问题的方法，其中基于轨迹长度的一维路径上的输出是一种新颖的表达形式。实验得出：（1）计算的函数复杂度随深度指数增长；（2）所有权重不同，加上轨迹正则化是批标准化的一个更简单的选择，但表现相同。

深度神经网络的表现力