The big empirical success of group equivariant networks has led in recent years to the sprouting of a great variety of equivariant network architectures. A particular focus has thereby been on rotation and reflection equivariant CNNs for planar images. Here we give a general description of $E(2)$-equivariant convolutions in the framework of Steerable CNNs. The theory of Steerable CNNs thereby yields constraints on the convolution kernels which depend on group representations describing the transformation laws of feature spaces. We show that these constraints for arbitrary group representations can be reduced to constraints under irreducible representations. A general solution of the kernel space constraint is given for arbitrary representations of the Euclidean group $E(2)$ and its subgroups. We implement a wide range of previously proposed and entirely new equivariant network architectures and extensively compare their performances. $E(2)$-steerable convolutions are further shown to yield remarkable gains on CIFAR-10, CIFAR-100 and STL-10 when used as a drop-in replacement for non-equivariant convolutions.

该研究描述了在可旋转卷积神经网络框架中的$E(2)$-等变卷积，提出了转换特性表示描述特征空间变换法则的群表示。研究人员证明了这些约束可以通过使用不可约表示约简为任意群表示的约束，并通过实现一系列先前提出的和全新的等变网络架构进行了广泛比较，表明当用作非等变卷积的替代品时，在CIFAR-10、CIFAR-100和STL-10上使用$E(2)$-可旋转卷积可以取得显著的改进。

广义E（2）等变可转CNN