We investigate the representation power of graph neural networks in the semi-supervised node classification task under heterophily or low homophily, i.e., in networks where connected nodes may have different class labels and dissimilar features. Most existing GNNs fail to generalize to this setting, and are even outperformed by models that ignore the graph structure (e.g., multilayer perceptrons). Motivated by this limitation, we identify a set of key designs -- ego- and neighbor-embedding separation, higher-order neighborhoods, and combination of intermediate representations -- that boost learning from the graph structure under heterophily, and combine them into a new graph convolutional neural network, H2GCN. Going beyond the traditional benchmarks with strong homophily, our empirical analysis on synthetic and real networks shows that, thanks to the identified designs, H2GCN has consistently strong performance across the full spectrum of low-to-high homophily, unlike competitive prior models without them.

该研究通过节约和邻居嵌入、高阶邻居和中间表示的结合，设计出一种草图神经网络（H2GCN），并通过实验表明其在半监督节点分类任务下，具有比传统模型更高的预测准确率，尤其对于异质性网络（即一对连接的节点可能具有不同的类别标签和不同的特征）表现更出色。

图神经网络中超越同构性：现有限制与有效设计