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Eight Methods to Evaluate Robust Unlearning in LLMs

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arxiv 2402.16835 v1 pith:TDVPYQ7V submitted 2024-02-26 cs.CL

Eight Methods to Evaluate Robust Unlearning in LLMs

classification cs.CL
keywords unlearningmodelcomprehensiveeldanharryknowledgellmsmethods
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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Machine unlearning can be useful for removing harmful capabilities and memorized text from large language models (LLMs), but there are not yet standardized methods for rigorously evaluating it. In this paper, we first survey techniques and limitations of existing unlearning evaluations. Second, we apply a comprehensive set of tests for the robustness and competitiveness of unlearning in the "Who's Harry Potter" (WHP) model from Eldan and Russinovich (2023). While WHP's unlearning generalizes well when evaluated with the "Familiarity" metric from Eldan and Russinovich, we find i) higher-than-baseline amounts of knowledge can reliably be extracted, ii) WHP performs on par with the original model on Harry Potter Q&A tasks, iii) it represents latent knowledge comparably to the original model, and iv) there is collateral unlearning in related domains. Overall, our results highlight the importance of comprehensive unlearning evaluation that avoids ad-hoc metrics.

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Cited by 21 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. DurableUn: Quantization-Induced Recovery Attacks in Machine Unlearning

    cs.LG 2026-05 conditional novelty 8.0

    INT4 quantization recovers up to 22 times more forgotten training data in unlearned LLMs, and the proposed DURABLEUN-SAF method is the first to maintain forgetting across BF16, INT8, and INT4 precisions.

  2. Forget Narrowly, Retain Broadly: Unlearning as an Asymmetric Generalization Problem

    cs.LG 2026-07 accept novelty 7.0

    SUITE defines the forget-retain boundary at semantic, syntactic and lexical levels; training on it plus JensUn++ yields near-complete forgetting with minimal retain and utility loss.

  3. Measuring the Depth of LLM Unlearning via Activation Patching

    cs.CL 2026-05 unverdicted novelty 7.0

    Introduces Unlearning Depth Score (UDS) via activation patching to quantify LLM unlearning depth and claims it outperforms 20 other metrics in faithfulness and robustness on 150 models.

  4. Locking Pretrained Weights via Deep Low-Rank Residual Distillation

    cs.LG 2026-05 unverdicted novelty 7.0

    DLR-Lock locks open-weight LLMs against unauthorized fine-tuning by swapping MLPs for deep low-rank residual networks that inflate backprop memory and complicate optimization, yet preserve original capabilities via mo...

  5. DurableUn: Quantization-Induced Recovery Attacks in Machine Unlearning

    cs.LG 2026-05 unverdicted novelty 7.0

    INT4 quantization recovers forgotten data in unlearned LLMs up to 22x, exposing a trilemma with no existing method solving forgetting, utility, and robustness together; a new sharpness-aware method achieves cross-prec...

  6. Efficient Unlearning through Maximizing Relearning Convergence Delay

    cs.LG 2026-04 unverdicted novelty 7.0

    The Influence Eliminating Unlearning framework maximizes relearning convergence delay via weight decay and noise injection to remove the influence of a forgetting set while preserving accuracy on retained data.

  7. Is your algorithm unlearning or untraining?

    cs.LG 2026-04 conditional novelty 7.0

    Machine unlearning conflates reversing the influence of specific training examples (untraining) with removing the full underlying distribution or behavior (unlearning).

  8. Improving LLM Unlearning Robustness via Random Perturbations

    cs.CL 2025-01 unverdicted novelty 7.0

    LLM unlearning is reframed as inadvertently installing backdoor triggers on forget-tokens; Random Noise Augmentation is introduced as a defense that improves robustness with theoretical guarantees.

  9. Reinforcing Dual-Path Reasoning in Spatial Vision Language Models

    cs.CV 2026-06 unverdicted novelty 6.0

    SR-REAL equips spatial VLMs with dual LOR and DTR reasoning paths trained via RL, achieving better benchmark performance through mutual reinforcement and generalization without per-task tuning.

  10. RepSelect: Robust LLM Unlearning via Representation Selectivity

    cs.CL 2026-06 unverdicted novelty 6.0

    RepSelect isolates forget-set-specific representations via gradient PCA collapse to achieve 4-50x better post-relearning robustness than baselines across multiple models and forget categories.

  11. Multilingual Unlearning in LLMs: Transfer, Dynamics, and Reversibility

    cs.CL 2026-06 unverdicted novelty 6.0

    Unlearning in multilingual LLMs suppresses rather than erases knowledge in later layers, with transfer varying by language similarity and reversible via inference-time steering.

  12. Auditing Reasoning-Trace Memorization Claims after Unlearning with Head-Conditioned Canaries

    cs.LG 2026-05 conditional novelty 6.0

    Swapping the reasoning trace prefill on unlearned weights can replicate or reverse the parser-split bypass gap, showing that the gap alone does not identify or rule out weight-level memorization.

  13. Distinguishable Deletion: Unifying Knowledge Erasure and Refusal for Large Language Model Unlearning

    cs.LG 2026-05 unverdicted novelty 6.0

    Distinguishable Deletion unifies knowledge erasure and refusal for LLM unlearning via an energy index that enforces boundaries during training and enables refusal at inference.

  14. Robust LLM Unlearning Against Relearning Attacks: The Minor Components in Representations Matter

    cs.CL 2026-05 unverdicted novelty 6.0

    Targeting minor components in LLM representations during unlearning yields substantially better resistance to relearning attacks than prior methods.

  15. Probe-Geometry Alignment: Erasing the Cross-Sequence Memorization Signature Below Chance

    cs.LG 2026-05 unverdicted novelty 6.0

    Probe-geometry alignment erases cross-sequence memorization signatures in LLMs below chance using per-depth rank-one activation interventions with negligible impact on zero-shot capabilities.

  16. Representation-Guided Parameter-Efficient LLM Unlearning

    cs.CL 2026-04 unverdicted novelty 6.0

    REGLU guides LoRA-based unlearning via representation subspaces and orthogonal regularization to outperform prior methods on forget-retain trade-off in LLM benchmarks.

  17. WIN-U: Woodbury-Informed Newton-Unlearning as a retain-free Machine Unlearning Framework

    cs.LG 2026-04 unverdicted novelty 6.0

    WIN-U delivers a retain-free unlearning update that approximates the gold-standard retrained model via a Woodbury-informed Newton step using only forget-set curvature information.

  18. Latent Instruction Representation Alignment: defending against jailbreaks, backdoors and undesired knowledge in LLMs

    cs.LG 2026-04 unverdicted novelty 6.0

    LIRA aligns latent instruction representations in LLMs to defend against jailbreaks, backdoors, and undesired knowledge, blocking over 99% of PEZ attacks and achieving optimal WMDP forgetting.

  19. Downgrade to Upgrade: Optimizer Simplification Enhances Robustness in LLM Unlearning

    cs.LG 2025-10 conditional novelty 6.0

    Downgrading optimizers to lower-information variants during LLM unlearning yields more robust forgetting on MUSE and WMDP benchmarks by converging to harder-to-perturb loss basins.

  20. Unlearning Isn't Deletion: Investigating Reversibility of Machine Unlearning in LLMs

    cs.CL 2025-05 unverdicted novelty 6.0

    Machine unlearning in LLMs is often reversible via fine-tuning, indicating suppression not deletion, and a new representation-level framework identifies four forgetting regimes based on reversibility and catastrophicity.

  21. Position: The Term "Machine Unlearning" Is Overused in LLMs

    cs.CL 2026-05 accept novelty 5.0

    Machine unlearning should be restricted to dataset-defined deletion achieving retraining equivalence, while other LLM tasks require separate terminology and evaluation baselines.