Forgetting User Preference in Recommendation Systems with Label-Flipping

Recommendation systems play a crucial role in identifying users’ preferences based on their historical interaction records and those of other users. However, the ability to “forget” certain users’ preferences is indispensable for ensuring user privacy and maintaining recommendation accuracy. It is essential to accommodate a user’s request to exclude their behavioral data from the recommendation system when necessary. Likewise, if certain data corrupts the system, its impact should be removed to restore system performance. In this paper, we propose FlipRec, a general and efficient framework for recommendation models to “forget” the preferences of specific users while retaining the model’s performance for all other users. Our concept of forgetting user preferences is inspired by the label-flipping attack, a technique where the labels of some training samples are inverted to adversarially manipulate the weights of the trained model. FlipRec adjusts the recommendation model weights to forget the targeted users by flipping their interaction records $y \in \{ 0,1\}$. To preserve the model’s performance for the remaining users, we augment the fine-tuning data with samples from users who have interacted with the same items as the targeted users. This ensures minimal impact on these users during the “forgetting” process. FlipRec has been validated on both contentbased recommendation models and collaborative filtering models. The experimental results show that FlipRec outperforms stateof-the-art unlearning methods in terms of efficiency, the ability to forget targeted users, and the preservation of performance for the remaining users.