Hierarchical Federated Unlearning for Large Language Models

Fuente: arXiv
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Auteurs principaux: Zhong, Yisheng, Yang, Zhengbang, Zhu, Zhuangdi
Format: Preprint
Publié: 2025
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author Zhong, Yisheng
Yang, Zhengbang
Zhu, Zhuangdi
author_facet Zhong, Yisheng
Yang, Zhengbang
Zhu, Zhuangdi
contents Large Language Models (LLMs) are increasingly integrated into real-world applications, raising concerns about privacy, security and the need to remove undesirable knowledge. Machine Unlearning has emerged as a promising solution, yet faces two key challenges: (1) practical unlearning needs are often continuous and heterogeneous, and (2) they involve decentralized, sensitive data with asymmetric access. These factors result in inter-domain and intra-domain interference, which further amplifies the dilemma of unbalanced forgetting and retaining performance. In response, we propose a federated unlearning approach for LLMs that is scalable and privacy preserving. Our method decouples unlearning and retention via task-specific adapter learning and employs a hierarchical merging strategy to mitigate conflicting objectives and enables robust, adaptable unlearning updates. Comprehensive experiments on benchmarks of WMDP, MUSE, and TOFU showed that our approach effectively handles heterogeneous unlearning requests while maintaining strong LLM utility compared with baseline methods.
format Preprint
id arxiv_https___arxiv_org_abs_2510_17895
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Hierarchical Federated Unlearning for Large Language Models
Zhong, Yisheng
Yang, Zhengbang
Zhu, Zhuangdi
Machine Learning
Artificial Intelligence
Computation and Language
Large Language Models (LLMs) are increasingly integrated into real-world applications, raising concerns about privacy, security and the need to remove undesirable knowledge. Machine Unlearning has emerged as a promising solution, yet faces two key challenges: (1) practical unlearning needs are often continuous and heterogeneous, and (2) they involve decentralized, sensitive data with asymmetric access. These factors result in inter-domain and intra-domain interference, which further amplifies the dilemma of unbalanced forgetting and retaining performance. In response, we propose a federated unlearning approach for LLMs that is scalable and privacy preserving. Our method decouples unlearning and retention via task-specific adapter learning and employs a hierarchical merging strategy to mitigate conflicting objectives and enables robust, adaptable unlearning updates. Comprehensive experiments on benchmarks of WMDP, MUSE, and TOFU showed that our approach effectively handles heterogeneous unlearning requests while maintaining strong LLM utility compared with baseline methods.
title Hierarchical Federated Unlearning for Large Language Models
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2510.17895