Quaternion Graph Neural Networks

Recently, graph neural networks (GNNs) have become an important and active research direction in deep learning. It is worth noting that most of the existing GNN-based methods learn graph representations within the Euclidean vector space. Beyond the Euclidean space, learning representation and embeddings in hyper-complex space have also shown to be a promising and effective approach. To this end, we propose Quaternion Graph Neural Networks (QGNN) and Gated Quaternion Graph Neural Networks (GQGNN) to learn graph representations within the Quaternion space. As demonstrated, the Quaternion space, a hyper-complex vector space, provides highly meaningful computations and analogical calculus through Hamilton product compared to the Euclidean and complex vector spaces. Our QGNN obtains state-of-the-art results on a range of benchmark datasets for graph classification and node classification. Besides, regarding knowledge graphs, our QGNN-based knowledge graph embedding method gets state-of-the-art results on three new and challenging benchmark datasets for knowledge graph completion. Furthermore, regarding text graphs, our GQGNN-based text classification method works better than state-of-the-art methods on benchmark datasets for inductive text classification. Our code is available at: \url{https://github.com/daiquocnguyen/QGNN}.