Appendix A Related Work

For the latter, PT -based methods adaptively extract a matching width-based slimmed-down sub-model from the global model as a local model according to each client's budget, thus averting the requirements for public data. As with FedAvg, PT -based methods require the server to periodically communicate with the clients. Existing PT -based methods focus on how to extract width-based sub-models from the global model. DFKD methods are promising, which transfer knowledge from the teacher model to another student model without any real data. Existing DFKD methods can be broadly classified into non-adversarial and adversarial training methods. They take the quality and/or diversity of the synthetic data as important objectives.