Latent Coreset Sampling based Data-Free Continual Learning

Abstract

Catastrophic forgetting poses a major challenge in continual learning where the old knowledge is forgotten when the model is updated on new tasks. Existing solutions tend to solve this challenge through generative models or exemplar-replay strategies. However, such methods may not alleviate the issue that the low-quality samples are generated or selected for the replay, which would directly reduce the effectiveness of the model, especially in the class imbalance, noise, or redundancy scenarios. Accordingly, how to select a suitable coreset during continual learning becomes significant in such setting. In this work, we propose a novel approach that leverages continual coreset sampling (CCS) to address these challenges. We aim to select the most representative subsets during each iteration. When the model is trained on new tasks, it closely approximates/matches the gradient of both the previous and current tasks with respect to the model parameters. This way, adaptation of the model to new datasets could be more efficient. Furthermore, different from the old data storage for maintaining the old knowledge, our approach choose to preserving them in the latent space. We augment the previous classes in the embedding space as the pseudo sample vectors from the old encoder output, strengthened by the joint training with selected new data. It could avoid data privacy invasions in a real-world application when we update the model. Our experiments validate the effectiveness of our proposed approach over various CV/NLP datasets under against current baselines, and we also indicate the obvious improvement of model adaptation and forgetting reduction in a data-free manner.