In this paper we show how Group Equivariant Convolutional Neural Networks use subsampling to learn to break equivariance to their symmetries. We focus on 2D rotations and reflections and investigate the impact of broken equivariance on network performance. We show that a change in the input dimension of a network as small as a single pixel can be enough for commonly used architectures to become approximately equivariant, rather than exactly. We investigate the impact of networks not being exactly equivariant and find that approximately equivariant networks generalise significantly worse to unseen symmetries compared to their exactly equivariant counterparts. However, when the symmetries in the training data are not identical to the symmetries of the network, we find that approximately equivariant networks are able to relax their own equivariant constraints, causing them to match or outperform exactly equivariant networks on common benchmark datasets.

我们研究了群等变卷积神经网络如何使用子采样来打破对其对称性的等变性，并探讨了对网络性能的影响。我们发现，即使输入维度只有一个像素的微小变化，常用的架构也会变得近似等变，而不是完全等变。当训练数据中的对称性与网络的对称性不完全相同时，近似等变网络能够放松其等变性约束，并在常见的基准数据集上与或胜过完全等变网络。

使用与滥用等变性