arXiv AI

DISCERN: Distributional Synthetic Replay for Retain-Free Incremental Machine Unlearning

DISCERN is a class‑unlearning method that replaces real data with synthetic embeddings drawn from per‑class parametric distributions, selecting the best fit via statistical tests or cross‑validated likelihood. Unlike prototype replay, it models both Euclidean (Gaussian, Laplace, Student’s t) and directional (von Mises–Fisher, Fisher–Bingham) families to capture the latent geometry of transformer embeddings, which lie on a hypersphere. Experiments on MNIST, CIFAR‑10, and CIFAR‑100 with convolutional and transformer backbones show DISCERN performs competitively in simultaneous deletions and remains the most stable in incremental class unlearning, especially on ViT‑B/16 where it maintains a high harmonic mean after 20 sequential deletions.

arXiv Machine Learning
Sep 3

Source-Free Class Relearning: Diagnosing Forgetting in Class Unlearning

The paper investigates whether a model that has undergone class unlearning can still recover forgotten classes without access to original data. It introduces a white‑box audit method that generates synthetic probes in representation space, filters them by confidence, and relabels boundary‑adjacent probes as the forgotten class. The authors define a Relearning Score to quantify recovery while preserving retain performance, and demonstrate that several unlearning techniques on CIFAR‑10, CIFAR‑100, and TinyImageNet can be fully recovered in a source‑free setting, sometimes even outperforming a retrained reference.

By Zahra Dehghani, Pablo Piantanida, Mohammadhadi Shateri
arXiv Machine Learning
Sep 30

Reference-Guided Machine Unlearning

Reference-Guided Machine Unlearning (ReGUn) is a vision unlearning framework that prioritizes distributional indistinguishability over degradation-based heuristics. It uses disjoint held-out data to create a class-conditioned reference distribution for distillation, guiding forget samples toward non-member behavior without explicitly degrading predictions. Experiments across various architectures and datasets show that ReGUn achieves a competitive forgetting–utility trade-off and closely matches retrain-like membership inference behavior.

By Jonas Mirlach, Sonia Laguna, Julia E. Vogt
arXiv AI
Jun 3

PURGE: Projected Unlearning via Retain-Guided Erasure

arXiv:2606. 03808v1 Announce Type: cross Abstract: We propose PURGE, a machine unlearning algorithm built on a simple but an under-exploited observation: continual learning (CL) and machine unlearning (MU) which are fundamentally dual problems.

By Vedant Jawandhia, Daksh Ahuja, Ghufran Alam Siddiqui, Prashant Trivedi, Yash Sinha, Pratik Narang
arXiv Machine Learning
Oct 7

What Must Replay Preserve? Separating Correctable Bias from Class Correspondence

The paper investigates what information must be preserved in replay buffers for class‑incremental learning. By treating cached predictions as temporally heterogeneous supervision, the authors separate classes known at storage time from those learned later, and evaluate the impact of deleting logit matching. Experiments on CIFAR‑100 with DER++ show that a simple task‑level offset can largely correct the cost of removing later‑class matching, while the cost of disrupting class correspondence remains.

By BoRen Deng, Xiangyue Ma, Chenglong Li, Xiaoting Du
arXiv Machine Learning
Oct 5

Fisher-Guided Submodular Data Selection for Continual Pre-Training of Large Language Models

The paper introduces a Fisher-guided submodular data selection method for continual pre‑training of large language models, addressing the forgetting problem that arises when a target‑domain corpus overwrites pretrained knowledge. By decomposing candidate gradients into anchor and frontier components and optimizing a log‑determinant submodular objective, the method selects data that both improves target‑domain performance and limits forgetting. Experiments on TinyLlama‑1.1B and Llama‑3.1‑8B show that the selector achieves superior adaptation and forgetting control while using ten times fewer tokens than traditional replay strategies.

By Zhenghao Zhao, Gaowen Liu, Zhiling Lan, Yan Yan
arXiv AI
Oct 1

Unmerge: Efficient Machine Unlearning via Task Arithmetic

The paper introduces Unmerge, an efficient machine unlearning algorithm that treats unlearning as the inverse of task arithmetic. By representing the forget component as a low‑rank basis at each layer, Unmerge optimizes three goals—matching the merged vector, suppressing leakage, and bounding correction size—to limit forget leakage and retain damage. Experiments on ResNet‑50, ViT‑S/16, and Llama‑3.2‑3B show significant performance gains over existing methods while maintaining privacy and feature‑distribution fidelity.

By Haoran Tang, Andrew Tan, Rajiv Khanna