Federated Unlearning in the Wild: Rethinking Fairness and Data Discrepancy

Fuente: arXiv
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Autori principali: Huang, ZiHeng, Wu, Di, Bai, Jun, Zhang, Jiale, Cao, Sicong, Zhang, Ji, Hu, Yingjie
Natura: Preprint
Pubblicazione: 2025
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author Huang, ZiHeng
Wu, Di
Bai, Jun
Zhang, Jiale
Cao, Sicong
Zhang, Ji
Hu, Yingjie
author_facet Huang, ZiHeng
Wu, Di
Bai, Jun
Zhang, Jiale
Cao, Sicong
Zhang, Ji
Hu, Yingjie
contents Machine unlearning is critical for enforcing data deletion rights like the "right to be forgotten." As a decentralized paradigm, Federated Learning (FL) also requires unlearning, but realistic implementations face two major challenges. First, fairness in Federated Unlearning (FU) is often overlooked. Exact unlearning methods typically force all clients into costly retraining, even those uninvolved. Approximate approaches, using gradient ascent or distillation, make coarse interventions that can unfairly degrade performance for clients with only retained data. Second, most FU evaluations rely on synthetic data assumptions (IID/non-IID) that ignore real-world heterogeneity. These unrealistic benchmarks obscure the true impact of unlearning and limit the applicability of current methods. We first conduct a comprehensive benchmark of existing FU methods under realistic data heterogeneity and fairness conditions. We then propose a novel, fairness-aware FU approach, Federated Cross-Client-Constrains Unlearning (FedCCCU), to explicitly address both challenges. FedCCCU offers a practical and scalable solution for real-world FU. Experimental results show that existing methods perform poorly in realistic settings, while our approach consistently outperforms them.
format Preprint
id arxiv_https___arxiv_org_abs_2510_07022
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Federated Unlearning in the Wild: Rethinking Fairness and Data Discrepancy
Huang, ZiHeng
Wu, Di
Bai, Jun
Zhang, Jiale
Cao, Sicong
Zhang, Ji
Hu, Yingjie
Machine Learning
Artificial Intelligence
Machine unlearning is critical for enforcing data deletion rights like the "right to be forgotten." As a decentralized paradigm, Federated Learning (FL) also requires unlearning, but realistic implementations face two major challenges. First, fairness in Federated Unlearning (FU) is often overlooked. Exact unlearning methods typically force all clients into costly retraining, even those uninvolved. Approximate approaches, using gradient ascent or distillation, make coarse interventions that can unfairly degrade performance for clients with only retained data. Second, most FU evaluations rely on synthetic data assumptions (IID/non-IID) that ignore real-world heterogeneity. These unrealistic benchmarks obscure the true impact of unlearning and limit the applicability of current methods. We first conduct a comprehensive benchmark of existing FU methods under realistic data heterogeneity and fairness conditions. We then propose a novel, fairness-aware FU approach, Federated Cross-Client-Constrains Unlearning (FedCCCU), to explicitly address both challenges. FedCCCU offers a practical and scalable solution for real-world FU. Experimental results show that existing methods perform poorly in realistic settings, while our approach consistently outperforms them.
title Federated Unlearning in the Wild: Rethinking Fairness and Data Discrepancy
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2510.07022