Group Equivariant CNNs (G-CNNs) have shown promising efficacy in various tasks, owing to their ability to capture hierarchical features in an equivariant manner. However, their equivariance is fixed to the symmetry of the whole group, limiting adaptability to diverse partial symmetries in real-world datasets, such as limited rotation symmetry of handwritten digit images and limited color-shift symmetry of flower images. Recent efforts address this limitation, one example being Partial G-CNN which restricts the output group space of convolution layers to break full equivariance. However, such an approach still fails to adjust equivariance levels across data. In this paper, we propose a novel approach, Variational Partial G-CNN (VP G-CNN), to capture varying levels of partial equivariance specific to each data instance. VP G-CNN redesigns the distribution of the output group elements to be conditioned on input data, leveraging variational inference to avoid overfitting. This enables the model to adjust its equivariance levels according to the needs of individual data points. Additionally, we address training instability inherent in discrete group equivariance models by redesigning the reparametrizable distribution. We demonstrate the effectiveness of VP G-CNN on both toy and real-world datasets, including MNIST67-180, CIFAR10, ColorMNIST, and Flowers102. Our results show robust performance, even in uncertainty metrics.

提出了一种新颖方法 Variational Partial G-CNN (VP G-CNN)，用于捕捉每个数据实例特定的不同水平的部分等变性。VP G-CNN重新设计了输出组元素的分布，以便在输入数据上进行条件设置，利用变分推断避免过拟合。此外，通过重新设计可重参数化分布，解决了离散群等变性模型中存在的训练不稳定性问题。在玩具数据集和实际数据集上（包括MNIST67-180、CIFAR10、ColorMNIST和Flowers102），结果表明VP G-CNN具有鲁棒的性能，即使在不确定性度量方面也是如此。

输入感知的局部群卷积变分用于旋转和颜色偏移的局部等变性