How Hard Can It Be? Hardness-Aware Multi-Objective Unlearning

Fuente: arXiv
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Autori principali: Chen, Jiangwei, Niu, Xinyuan, Sim, Rachael Hwee Ling, Liu, Zhengyuan, Chen, Nancy F., Low, Bryan Kian Hsiang
Natura: Preprint
Pubblicazione: 2026
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author Chen, Jiangwei
Niu, Xinyuan
Sim, Rachael Hwee Ling
Liu, Zhengyuan
Chen, Nancy F.
Low, Bryan Kian Hsiang
author_facet Chen, Jiangwei
Niu, Xinyuan
Sim, Rachael Hwee Ling
Liu, Zhengyuan
Chen, Nancy F.
Low, Bryan Kian Hsiang
contents Machine unlearning aims to remove the influence of specific forget training data due to privacy, copyright or bias concerns while maintaining the model performance on the remaining retain data. Existing unlearning algorithms, such as optimizing a weighted combination of losses, have tried to achieve these objectives of improving forget quality and maintaining retain utility. However, they do not guarantee that these objectives can be improved by a specified extent for all forget and retain data. In this work, we address this limitation with a novel and theoretically-grounded approach from a constrained optimization perspective. Firstly, we identify that the hardness of reconciling both objectives can be quantified by the similarity between the forget data and the retain data. Next, we derive an unlearning algorithm (HAMU) with the overall goal of guaranteeing a specified improvement in forget quality while minimizing the retain utility cost/degradation by updating the model weights based on our hardness measure. Our hardness measure also informs users when retain utility degradation is unavoidable, i.e., both objectives cannot be improved simultaneously, and stopping should be considered. Our algorithm is applicable to non-convex models and is easily parallelizable, making it readily deployable in real-world scenarios. We empirically demonstrate HAMU's superior performance over baselines on both image and text datasets using large models. Our code is available at https://github.com/aoi3142/HAMU.
format Preprint
id arxiv_https___arxiv_org_abs_2606_02119
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle How Hard Can It Be? Hardness-Aware Multi-Objective Unlearning
Chen, Jiangwei
Niu, Xinyuan
Sim, Rachael Hwee Ling
Liu, Zhengyuan
Chen, Nancy F.
Low, Bryan Kian Hsiang
Machine Learning
Artificial Intelligence
Machine unlearning aims to remove the influence of specific forget training data due to privacy, copyright or bias concerns while maintaining the model performance on the remaining retain data. Existing unlearning algorithms, such as optimizing a weighted combination of losses, have tried to achieve these objectives of improving forget quality and maintaining retain utility. However, they do not guarantee that these objectives can be improved by a specified extent for all forget and retain data. In this work, we address this limitation with a novel and theoretically-grounded approach from a constrained optimization perspective. Firstly, we identify that the hardness of reconciling both objectives can be quantified by the similarity between the forget data and the retain data. Next, we derive an unlearning algorithm (HAMU) with the overall goal of guaranteeing a specified improvement in forget quality while minimizing the retain utility cost/degradation by updating the model weights based on our hardness measure. Our hardness measure also informs users when retain utility degradation is unavoidable, i.e., both objectives cannot be improved simultaneously, and stopping should be considered. Our algorithm is applicable to non-convex models and is easily parallelizable, making it readily deployable in real-world scenarios. We empirically demonstrate HAMU's superior performance over baselines on both image and text datasets using large models. Our code is available at https://github.com/aoi3142/HAMU.
title How Hard Can It Be? Hardness-Aware Multi-Objective Unlearning
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2606.02119