Reviews: General E(2)-Equivariant Steerable CNNs

We had a discussion about this paper with the reviewers raising the question of novelty since the general topic of steerable neural networks (i.e., equivariant neural networks where the activations are defined as a function on a homogeneous space) has now been thoroughly explored in the literature. Also, Weiler et al have a paper on SE(3) equivariant nets, so the E(2) is arguably just a simpler variant. There are three reasons why I nonetheless recommend this paper for acceptance: 1. The kernel constraint conditions are meticulously worked out for a range of specific subgroups of O(2). One wonders whether this could be done more generally and whether it really requires so much tedious algebra.