DualFed: Enjoying both Generalization and Personalization in Federated Learning via Hierachical Representations

TL;DR

DualFed introduces a hierarchical representation approach in federated learning that simultaneously achieves high model generalization and personalization by separating shared and task-specific features.

Contribution

The paper proposes DualFed, a novel method that uses a personalized projection network to obtain dual representations, enabling concurrent generalization and personalization in federated learning.

Findings

Outperforms existing federated learning methods in experiments

Effectively separates shared and task-specific information

Reduces mutual interference between generalization and personalization

Abstract

In personalized federated learning (PFL), it is widely recognized that achieving both high model generalization and effective personalization poses a significant challenge due to their conflicting nature. As a result, existing PFL methods can only manage a trade-off between these two objectives. This raises an interesting question: Is it feasible to develop a model capable of achieving both objectives simultaneously? Our paper presents an affirmative answer, and the key lies in the observation that deep models inherently exhibit hierarchical architectures, which produce representations with various levels of generalization and personalization at different stages. A straightforward approach stemming from this observation is to select multiple representations from these layers and combine them to concurrently achieve generalization and personalization. However, the number of candidate representations is commonly huge, which makes this method infeasible due to high computational costs.To address this problem, we propose DualFed, a new method that can directly yield dual representations correspond to generalization and personalization respectively, thereby simplifying the optimization task. Specifically, DualFed inserts a personalized projection network between the encoder and classifier. The pre-projection representations are able to capture generalized information shareable across clients, and the post-projection representations are effective to capture task-specific information on local clients. This design minimizes the mutual interference between generalization and personalization, thereby achieving a win-win situation. Extensive experiments show that DualFed can outperform other FL methods. Code is available at https://github.com/GuogangZhu/DualFed.