KDGCN: A Kernel-based Double-level Graph Convolution Network for Semi-supervised Graph Classification with Scarce Labels

20 Sept 2023 (modified: 11 Feb 2024)Submitted to ICLR 2024EveryoneRevisionsBibTeX
Primary Area: unsupervised, self-supervised, semi-supervised, and supervised representation learning
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Keywords: graph neural network, graph classification, semi-supervised learning
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Abstract: Graph classification, which is significant in various fields, often faces the challenge of label scarcity. Under such a scenario, supervised methods based on graph neural networks do not perform well because they only utilize information from labeled data. Meanwhile, semi-supervised methods based on graph contrastive learning often yield complex models as well as elaborate hyperparameter-tuning. In this work, we present a novel semi-supervised graph classification method, which combines GCN modules with graph kernels such as Weisfeiler-Lehman subtree kernel. First, we use a GCN module as well as a readout operation to attain a graph feature vector for each graph in the dataset. Then, we view the graphs as meta-nodes of a supergraph constructed by a graph kernel among graphs. Finally, we use another GCN module, whose inputs are the graph feature vectors, to learn meta-node representations over the supergraph in a semi-supervised manner. Note that the two GCN modules are optimized jointly. Compared to contrastive learning based semi-supervised graph classification methods, our method has fewer hyperparameters and is easier to implement. Experiments on seven benchmark datasets demonstrate the effectiveness of our method in comparison to many baselines including supervised GCNs, label propagation, graph contrastive learning, etc.
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Submission Number: 2196
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