General Incremental Learning with Domain-aware Categorical Representations
This work addresses continual learning challenges for AI agents in real-world applications, but it is incremental as it builds on existing methods to handle more complex distribution shifts.
The paper tackles the problem of general incremental learning where both class and domain distributions change over time, addressing intra-class stability-plasticity and domain imbalance issues, and shows that their method outperforms previous approaches on benchmarks like iDigits, iDomainNet, and iCIFAR-20.
Continual learning is an important problem for achieving human-level intelligence in real-world applications as an agent must continuously accumulate knowledge in response to streaming data/tasks. In this work, we consider a general and yet under-explored incremental learning problem in which both the class distribution and class-specific domain distribution change over time. In addition to the typical challenges in class incremental learning, this setting also faces the intra-class stability-plasticity dilemma and intra-class domain imbalance problems. To address above issues, we develop a novel domain-aware continual learning method based on the EM framework. Specifically, we introduce a flexible class representation based on the von Mises-Fisher mixture model to capture the intra-class structure, using an expansion-and-reduction strategy to dynamically increase the number of components according to the class complexity. Moreover, we design a bi-level balanced memory to cope with data imbalances within and across classes, which combines with a distillation loss to achieve better inter- and intra-class stability-plasticity trade-off. We conduct exhaustive experiments on three benchmarks: iDigits, iDomainNet and iCIFAR-20. The results show that our approach consistently outperforms previous methods by a significant margin, demonstrating its superiority.