“…Significant attention has been paid towards developing federated optimization techniques. Such work has focused on various aspects, including communication-efficiency (Konečnỳ et al, 2016;McMahan et al, 2017;Basu et al, 2019;Laguel et al, 2021), data and systems heterogeneity (Li et al, 2020aKarimireddy et al, 2020b;Hsu et al, 2019;Karimireddy et al, 2020a;Li et al, 2020b;Li and Wang, 2019), and fairness (Li et al, 2020c;Hu et al, 2020). We provide a description of some relevant methods in Section 2, and defer readers to recent surveys such as (Kairouz et al, 2021) and (Li et al, 2020a) for additional background.…”