On the Implicit Adversariality of Catastrophic Forgetting in Deep Continual Learning

Fuente: arXiv
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Autori principali: Peng, Ze, Zhang, Jian, Guo, Jintao, Qi, Lei, Gao, Yang, Shi, Yinghuan
Natura: Preprint
Pubblicazione: 2025
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author Peng, Ze
Zhang, Jian
Guo, Jintao
Qi, Lei
Gao, Yang
Shi, Yinghuan
author_facet Peng, Ze
Zhang, Jian
Guo, Jintao
Qi, Lei
Gao, Yang
Shi, Yinghuan
contents Continual learning seeks the human-like ability to accumulate new skills in machine intelligence. Its central challenge is catastrophic forgetting, whose underlying cause has not been fully understood for deep networks. In this paper, we demystify catastrophic forgetting by revealing that the new-task training is implicitly an adversarial attack against the old-task knowledge. Specifically, the new-task gradients automatically and accurately align with the sharp directions of the old-task loss landscape, rapidly increasing the old-task loss. This adversarial alignment is intriguingly counter-intuitive because the sharp directions are too sparsely distributed to align with by chance. To understand it, we theoretically show that it arises from training's low-rank bias, which, through forward and backward propagation, confines the two directions into the same low-dimensional subspace, facilitating alignment. Gradient projection (GP) methods, a representative family of forgetting-mitigating methods, reduce adversarial alignment caused by forward propagation, but cannot address the alignment due to backward propagation. We propose backGP to address it, which reduces forgetting by 10.8% and improves accuracy by 12.7% on average over GP methods.
format Preprint
id arxiv_https___arxiv_org_abs_2510_09181
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Implicit Adversariality of Catastrophic Forgetting in Deep Continual Learning
Peng, Ze
Zhang, Jian
Guo, Jintao
Qi, Lei
Gao, Yang
Shi, Yinghuan
Machine Learning
Artificial Intelligence
Continual learning seeks the human-like ability to accumulate new skills in machine intelligence. Its central challenge is catastrophic forgetting, whose underlying cause has not been fully understood for deep networks. In this paper, we demystify catastrophic forgetting by revealing that the new-task training is implicitly an adversarial attack against the old-task knowledge. Specifically, the new-task gradients automatically and accurately align with the sharp directions of the old-task loss landscape, rapidly increasing the old-task loss. This adversarial alignment is intriguingly counter-intuitive because the sharp directions are too sparsely distributed to align with by chance. To understand it, we theoretically show that it arises from training's low-rank bias, which, through forward and backward propagation, confines the two directions into the same low-dimensional subspace, facilitating alignment. Gradient projection (GP) methods, a representative family of forgetting-mitigating methods, reduce adversarial alignment caused by forward propagation, but cannot address the alignment due to backward propagation. We propose backGP to address it, which reduces forgetting by 10.8% and improves accuracy by 12.7% on average over GP methods.
title On the Implicit Adversariality of Catastrophic Forgetting in Deep Continual Learning
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2510.09181