Learning Temporal Event Knowledge for Continual Social Event Classification

With the rapid development of Internet and the burgeoning scale of social media, Social Event Classification (SEC) has garnered increasing attention. The existing study of SEC focuses on recognizing a fixed set of social events. However, in real-world scenarios, new social events continually emerge on social media, which suggests the necessity for a practical SEC model that can swiftly adapt to the evolving environment with incremental social events. Therefore, in this paper, we study a new yet crucial problem defined as Continual Social Event Classification (C-SEC), where new events continually emerge in the sequentially collected social data. Accordingly, we propose a novel Temporal Event Knowledge Network (TEKNet) to continually learn temporal event knowledge for C-SEC with temporally incremental events. First, we conduct present event knowledge learning to learn the classification of newly emerging events in the presently incoming data. Second, we design past event knowledge replay with self-knowledge distillation to consolidate the learned knowledge of past events and prevent catastrophic forgetting. Finally, we propose future event knowledge pretraining with a modality mixture mechanism to pretrain the classifiers for events that occur in the future. Comprehensive experiments on real-world social event datasets demonstrate the superiority of our proposed TEKNet for C-SEC.