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Main Authors: Ma, Xin, Chen, Wei, Liu, Qi, Xu, Derong, Zheng, Zhi, Xu, Tong, Chen, Enhong
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.11836
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author Ma, Xin
Chen, Wei
Liu, Qi
Xu, Derong
Zheng, Zhi
Xu, Tong
Chen, Enhong
author_facet Ma, Xin
Chen, Wei
Liu, Qi
Xu, Derong
Zheng, Zhi
Xu, Tong
Chen, Enhong
contents Lifelong Model Editing aims to continuously update evolving facts in Large Language Models while preserving unrelated knowledge and general capabilities, yet it remains plagued by catastrophic forgetting and model collapse. Empirically, we find that recent editors resilient over long horizons share the same core strategy: Lifelong Normalization (LN), which normalizes value gradients using running statistics. Removing LN causes immediate performance collapse, and we observe a counter-intuitive positive cumulative effect where early edits can promote the success of future edits. Yet the mechanism of LN remains a "black box", leaving its precise role in lifelong stability poorly understood. In this work, we provide the first theoretical account of LN in the lifelong regime. Our analysis reveals a self-reinforcing stability loop and proves that, when combined with ridge-regularized regression, LN yields parameter updates with asymptotic orthogonality and bounded norms, directly mitigating forgetting and systemic collapse. Based on these insights, we derive StableEdit, which strengthens this stability loop via an explicit warm-up stage and full whitening, improving long-horizon stability at minimal overhead. Extensive experiments validate our theory and demonstrate competitive performance. Our code is available at https://github.com/MINE-USTC/StableEdit.
format Preprint
id arxiv_https___arxiv_org_abs_2605_11836
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle More Edits, More Stable: Understanding the Lifelong Normalization in Sequential Model Editing
Ma, Xin
Chen, Wei
Liu, Qi
Xu, Derong
Zheng, Zhi
Xu, Tong
Chen, Enhong
Machine Learning
Computation and Language
Lifelong Model Editing aims to continuously update evolving facts in Large Language Models while preserving unrelated knowledge and general capabilities, yet it remains plagued by catastrophic forgetting and model collapse. Empirically, we find that recent editors resilient over long horizons share the same core strategy: Lifelong Normalization (LN), which normalizes value gradients using running statistics. Removing LN causes immediate performance collapse, and we observe a counter-intuitive positive cumulative effect where early edits can promote the success of future edits. Yet the mechanism of LN remains a "black box", leaving its precise role in lifelong stability poorly understood. In this work, we provide the first theoretical account of LN in the lifelong regime. Our analysis reveals a self-reinforcing stability loop and proves that, when combined with ridge-regularized regression, LN yields parameter updates with asymptotic orthogonality and bounded norms, directly mitigating forgetting and systemic collapse. Based on these insights, we derive StableEdit, which strengthens this stability loop via an explicit warm-up stage and full whitening, improving long-horizon stability at minimal overhead. Extensive experiments validate our theory and demonstrate competitive performance. Our code is available at https://github.com/MINE-USTC/StableEdit.
title More Edits, More Stable: Understanding the Lifelong Normalization in Sequential Model Editing
topic Machine Learning
Computation and Language
url https://arxiv.org/abs/2605.11836