Graph Convolutional Network With Unknown Class Number

Xulun Ye, Jieyu Zhao

Abstract: The graph convolutional network (GCN), as a powerful tool in graph data processing, is widely exploited in many machine learning and computer vision tasks. However, existing GCNs usually assume that the network has fixed outputs, which is usually contrary to the real-world class number being unknown and incremental, leading to an open set classification problem in which the finite training dataset cannot contain all labels in the infinite testing data. To overcome these issues, a novel Bayesian model is proposed, in which we couple GCN and a deep generative clustering model in a unified framework. In our model, the GCN model is used to detect the known classes, the deep generative clustering model is designed to generate the novel classes, and a two-level label generative process is constructed to extend the finite GCN outputs to infinity and fuse the label generated by the GCN model and the deep generative model. Although posterior inference is difficult, our model leads to an efficient variational inference-based optimization method. Experiments on various datasets validate our theoretical analysis and demonstrate that our model can achieve state-of-the-art performance. Our source code has been released on the website.