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arXiv 2602.10568cs.LG

大语言模型时代的Gauss-Newton反学习

Gauss-Newton Unlearning for the LLM Era

University of Toronto(多伦多大学);MIT(麻省理工学院);Vector Institute for Artificial Intelligence(人工智能向量研究所)

Lev McKinney, Anvith Thudi, Juhan Bae, Tara Rezaei, Nicolas Papernot, Sheila A. McIlraith, Roger Grosse

AI总结:

K-FADE通过K-FAC近似实现大语言模型的高效反学习,减少遗忘集影响的同时保留保留集行为。

摘要:

标准的大语言模型训练可以生成在部署时产生训练者认为不可接受的输出的模型。使用诸如LLM反学习等方法可以降低这些输出出现的概率。然而,反学习一组数据(称为遗忘集)可能会降低模型在其他分布上的性能,而训练者希望保留模型的行为。为了改善这种权衡,我们证明使用遗忘集计算少量的向上Gauss-Newton步骤提供了一种概念上简单、最先进的LLM反学习方法。虽然Gauss-Newton步骤将牛顿法适应于非线性模型,但对LLM进行高效且准确的计算是具有挑战性的。因此,我们的方法关键依赖于参数Hessian近似,如Kronecker-因式近似曲率(K-FAC)。我们称这种结合方法为K-FADE(K-FAC用于分布擦除)。我们在WMDP和ToFU基准上的评估表明,K-FADE抑制了遗忘集的输出,并在输出空间中近似了不使用遗忘集重新训练的结果。关键的是,我们的方法在改变保留集的输出方面比先前的方法要少。这是因为K-FADE将模型在保留集上的输出约束转换为模型权重的约束,使算法能够在每一步最小化模型在保留集上的行为变化。此外,K-FADE计算的反学习更新可以在模型进一步训练时再次应用,使反学习能够以低成本维护。

英文摘要:

Standard large language model training can create models that produce outputs their trainer deems unacceptable in deployment. The probability of these outputs can be reduced using methods such as LLM unlearning. However, unlearning a set of data (called the forget set) can degrade model performance on other distributions where the trainer wants to retain the model's behavior. To improve this trade-off, we demonstrate that using the forget set to compute only a few uphill Gauss-Newton steps provides a conceptually simple, state-of-the-art unlearning approach for LLMs. While Gauss-Newton steps adapt Newton's method to non-linear models, it is non-trivial to efficiently and accurately compute such steps for LLMs. Hence, our approach crucially relies on parametric Hessian approximations such as Kronecker-Factored Approximate Curvature (K-FAC). We call this combined approach K-FADE (K-FAC for Distribution Erasure). Our evaluation on the WMDP and ToFU benchmarks demonstrates that K-FADE suppresses outputs from the forget set and approximates, in output space, the results of retraining without the forget set. Critically, our method does this while altering the outputs on the retain set less than previous methods. This is because K-FADE transforms a constraint on the model's outputs across the entire retain set into a constraint on the model's weights, allowing the algorithm to minimally change the model's behavior on the retain set at each step. Moreover, the unlearning updates computed by K-FADE can be reapplied later if the model undergoes further training, allowing unlearning to be cheaply maintained.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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