Title: Efficient Similarity-Based Fast Unlearning via Pearson Correlation Detection
Primary area: alignment, fairness, safety, privacy, and societal considerations
Keywords: Machine unlearning, Similarity detection, Pearson correlation coefficient

Abstract: Machine unlearning has emerged as a critical requirement for neural networks to selectively forget specific training data while preserving model performance on remaining data. However, existing approximate unlearning techniques are computationally expensive when applied repeatedly to remove multiple similar data points. This work introduces a fast, novel approach that leverages Pearson's correlation-based similarity detection to efficiently and rapidly unlearn data points that are similar to previously unlearned samples. Our fast unlearning method exploits the key observation that once a data point has been unlearned through approximate unlearning techniques, similar data points can be rapidly removed using a lightweight similarity-based approach without requiring the full computational overhead of the original unlearning procedure. 
We establish certain theoretical properties and assurances of our similarity-based unlearning approach. We demonstrate that by measuring Pearson's correlation between target data points and previously unlearned samples, we can identify candidates for efficient removal and apply an unlearning process. This approach significantly reduces computational costs for removing multiple related data points while maintaining comparable forgetting effectiveness. Our evaluation across four datasets demonstrates that the proposed method effectively unlearns correlated data points while maintaining model utility, providing a highly scalable solution for privacy-preserving machine learning systems. Experimental results show that our proposed approach shows an improvement $10^{-2}$ in terms of accuracy compared to state-of-the-art baselines.