Many interesting problems in machine learning are being revisited with new
deep learning tools. For graph-based semisupervised learning, a recent
important development is graph convolutional networks (GCNs), which nicely
integrate local vertex features and graph topology in the convolutional layers.
Although the GCN model compares favorably with other state-of-the-art methods,
its mechanisms are not clear and it still requires a considerable amount of
labeled data for validation and model selection. In this paper, we develop
deeper insights into the GCN model and address its fundamental limits. First,
we show that the graph convolution of the GCN model is actually a special form
of Laplacian smoothing, which is the key reason why GCNs work, but it also
brings potential concerns of over-smoothing with many convolutional layers.
Second, to overcome the limits of the GCN model with shallow architectures, we
propose both co-training and self-training approaches to train GCNs. Our
approaches significantly improve GCNs in learning with very few labels, and
exempt them from requiring additional labels for validation. Extensive
experiments on benchmarks have verified our theory and proposals.

本文研究机器学习领域的图半监督学习，提出了基于图卷积网络的深度学习方法，解决了图卷积网络机制不清晰及需要大量标注数据的问题，并针对浅层结构的限制提出了弱监督训练的方法。经过广泛实验验证，研究结果具有实际应用价值。