Online Continual Learning via Dynamic Expandable Recursive Model

The continual learning (CL) of novel concepts from new environments represents a popular and important topic aiming to manage catastrophic forgetting. Research studies have developed dynamic expansion models to deal with network forgetting in CL. Existing CL models usually explore the full capacity of activating parameters and representations while ignoring the previously learned representations when learning new tasks. In this paper, we propose a novel dynamic expansion model that incrementally accumulates and incorporates all previously learned representations into defining new experts to add to a mixture of experts in a recursive manner, aiming to reuse previously learned parameters and features to promote future task learning. We define a graph structure having each expert as a component node. We then propose a novel expandable expert graph attention mechanism that dynamically optimizes the graph when learning new tasks, maximizing the positive knowledge transfer. In addition, we propose a novel expert cooperation mechanism to promote the cooperation between all previous experts and with the currently updated expert. Furthermore, we propose a novel memory optimization approach, which encourages each expert to capture and learn completely different information, further improving performance. We provide the results of a series of experiments demonstrating that the proposed approach outperforms the state-of-the-art performance in CL.