KUDA: Knowledge Unlearning by Deviating Representation for Large Language Models

Fuente: arXiv
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Autores principales: Fang, Ce, Zhang, Zhikun, Chen, Min, Liu, Qing, Zhou, Lu, Liu, Zhe, Gao, Yunjun
Formato: Preprint
Publicado: 2026
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author Fang, Ce
Zhang, Zhikun
Chen, Min
Liu, Qing
Zhou, Lu
Liu, Zhe
Gao, Yunjun
author_facet Fang, Ce
Zhang, Zhikun
Chen, Min
Liu, Qing
Zhou, Lu
Liu, Zhe
Gao, Yunjun
contents Large language models (LLMs) acquire a large amount of knowledge through pre-training on vast and diverse corpora. While this endows LLMs with strong capabilities in generation and reasoning, it amplifies risks associated with sensitive, copyrighted, or harmful content in training data. LLM unlearning, which aims to remove specific knowledge encoded within models, is a promising technique to reduce these risks. However, existing LLM unlearning methods often force LLMs to generate random or incoherent answers due to their inability to alter the encoded knowledge precisely. To achieve effective unlearning at the knowledge level of LLMs, we propose Knowledge Unlearning by Deviating representAtion (KUDA). We first utilize causal tracing to locate specific layers for target knowledge storage. We then design a new unlearning objective that induces the model's representations to deviate from its original position in the phase of knowledge removal, thus disrupting the ability to associate with the target knowledge. To resolve the optimization conflicts between forgetting and retention, we employ a relaxation null-space projection mechanism to mitigate the disruption to the representation space of retaining knowledge. Extensive experiments on representative benchmarks, WMDP and MUSE, demonstrate that KUDA outperforms most existing baselines by effectively balancing knowledge removal and model utility retention.
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id arxiv_https___arxiv_org_abs_2602_19275
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle KUDA: Knowledge Unlearning by Deviating Representation for Large Language Models
Fang, Ce
Zhang, Zhikun
Chen, Min
Liu, Qing
Zhou, Lu
Liu, Zhe
Gao, Yunjun
Cryptography and Security
Large language models (LLMs) acquire a large amount of knowledge through pre-training on vast and diverse corpora. While this endows LLMs with strong capabilities in generation and reasoning, it amplifies risks associated with sensitive, copyrighted, or harmful content in training data. LLM unlearning, which aims to remove specific knowledge encoded within models, is a promising technique to reduce these risks. However, existing LLM unlearning methods often force LLMs to generate random or incoherent answers due to their inability to alter the encoded knowledge precisely. To achieve effective unlearning at the knowledge level of LLMs, we propose Knowledge Unlearning by Deviating representAtion (KUDA). We first utilize causal tracing to locate specific layers for target knowledge storage. We then design a new unlearning objective that induces the model's representations to deviate from its original position in the phase of knowledge removal, thus disrupting the ability to associate with the target knowledge. To resolve the optimization conflicts between forgetting and retention, we employ a relaxation null-space projection mechanism to mitigate the disruption to the representation space of retaining knowledge. Extensive experiments on representative benchmarks, WMDP and MUSE, demonstrate that KUDA outperforms most existing baselines by effectively balancing knowledge removal and model utility retention.
title KUDA: Knowledge Unlearning by Deviating Representation for Large Language Models
topic Cryptography and Security
url https://arxiv.org/abs/2602.19275