Review for NeurIPS paper: FedSplit: an algorithmic framework for fast federated optimization

Weaknesses: Main criticism: 1) The paper claims two main contributions, one of which is "The first contribution of this paper is to analyze some past procedures, and show that even in the favorable setting of deterministic updates (i.e., no stochastic approximation used), these methods typically fail to preserve solutions of the original optimization problem as fixed points " I believe the text above is misleading. In fact, it was already well known for the "past procedures" to not have the correct fixed points; one alternative approach to deal with such an issue was to incorporate the "drift"; see https://arxiv.org/abs/1910.06378 for example. Therefore, believe it would be more appropriate to not claim the contribution for showing the wrong fixed point of the local algorithms. Specifically, in strongly convex case (same arguments apply for weakly convex), the communication complexity of FedSplit is O(sqrt(kappa)log(1/epsilon)), which is identical to the communication complexity of AGD. In fact, AGD is favorable (in terms of the rate) as is requires a single gradient evaluation instead of evaluating the prox with high enough precision so that the inexactness does not drive the rate.