A Simple Yet Effective Layered Loss for Pre-Training of Network Embedding

Pre-training of network embedding aims to encode unlabeled node proximity into a low-dimensional space, where nodes are close to their neighbors while being far from negative samples. In recent years, Graph Neural Networks have shown groundbreaking performance in semi-supervised learning on the node classification and link prediction tasks. However, because of their inherent information aggregation pattern, almost all these methods can only obtain inferior embedding results in the pre-training of the unlabeled nodes. The margins between a target node and its multi-hop neighbors become hard distinguishable during node message aggregation. To address this problem, we propose a simple yet effective layered loss to combine with a graph attention network, dubbed as LlossNet, for pre-training. We regard the proximity of a target node and its two-hop neighbors as a unit (called a unit graph), where a target node is needed to be more closer to its direct neighbor than its two-hop neighbors. As such, LlossNet would be able to preserve the margins of nodes in the learned embedding space. Experimental results of various downstream tasks including classification and clustering demonstrate the effectiveness of our method on learning discriminative node representations.