FedFACT: A Provable Framework for Controllable Group-Fairness Calibration in Federated Learning

Fuente: arXiv
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Main Authors: Zhang, Li, Han, Zhongxuan, Feng, Xiaohua, Zhang, Jiaming, Li, Yuyuan, Chen, Chaochao
Format: Preprint
Published: 2025
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author Zhang, Li
Han, Zhongxuan
Feng, Xiaohua
Zhang, Jiaming
Li, Yuyuan
Chen, Chaochao
author_facet Zhang, Li
Han, Zhongxuan
Feng, Xiaohua
Zhang, Jiaming
Li, Yuyuan
Chen, Chaochao
contents With the emerging application of Federated Learning (FL) in decision-making scenarios, it is imperative to regulate model fairness to prevent disparities across sensitive groups (e.g., female, male). Current research predominantly focuses on two concepts of group fairness within FL: Global Fairness (overall model disparity across all clients) and Local Fairness (the disparity within each client). However, the non-decomposable, non-differentiable nature of fairness criteria poses two fundamental, unresolved challenges for fair FL: (i) Harmonizing global and local fairness, especially in multi-class setting; (ii) Enabling a controllable, optimal accuracy-fairness trade-off. To tackle these challenges, we propose a novel controllable federated group-fairness calibration framework, named FedFACT. FedFACT identifies the Bayes-optimal classifiers under both global and local fairness constraints, yielding models with minimal performance decline while guaranteeing fairness. Building on the characterization of the optimal fair classifiers, we reformulate fair federated learning as a personalized cost-sensitive learning problem for in-processing and a bi-level optimization for post-processing. Theoretically, we provide convergence and generalization guarantees for FedFACT to approach the near-optimal accuracy under given fairness levels. Extensive experiments on multiple datasets across various data heterogeneity demonstrate that FedFACT consistently outperforms baselines in balancing accuracy and global-local fairness.
format Preprint
id arxiv_https___arxiv_org_abs_2506_03777
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle FedFACT: A Provable Framework for Controllable Group-Fairness Calibration in Federated Learning
Zhang, Li
Han, Zhongxuan
Feng, Xiaohua
Zhang, Jiaming
Li, Yuyuan
Chen, Chaochao
Machine Learning
With the emerging application of Federated Learning (FL) in decision-making scenarios, it is imperative to regulate model fairness to prevent disparities across sensitive groups (e.g., female, male). Current research predominantly focuses on two concepts of group fairness within FL: Global Fairness (overall model disparity across all clients) and Local Fairness (the disparity within each client). However, the non-decomposable, non-differentiable nature of fairness criteria poses two fundamental, unresolved challenges for fair FL: (i) Harmonizing global and local fairness, especially in multi-class setting; (ii) Enabling a controllable, optimal accuracy-fairness trade-off. To tackle these challenges, we propose a novel controllable federated group-fairness calibration framework, named FedFACT. FedFACT identifies the Bayes-optimal classifiers under both global and local fairness constraints, yielding models with minimal performance decline while guaranteeing fairness. Building on the characterization of the optimal fair classifiers, we reformulate fair federated learning as a personalized cost-sensitive learning problem for in-processing and a bi-level optimization for post-processing. Theoretically, we provide convergence and generalization guarantees for FedFACT to approach the near-optimal accuracy under given fairness levels. Extensive experiments on multiple datasets across various data heterogeneity demonstrate that FedFACT consistently outperforms baselines in balancing accuracy and global-local fairness.
title FedFACT: A Provable Framework for Controllable Group-Fairness Calibration in Federated Learning
topic Machine Learning
url https://arxiv.org/abs/2506.03777