Tackling higher-order relations and heterogeneity: Dynamic heterogeneous hypergraph network for spatiotemporal activity prediction.

Spatiotemporal activity prediction aims to predict user activities at a particular time and location, which is applicable in city planning, activity recommendations, and other domains. The fundamental endeavor in spatiotemporal activity prediction is to model the intricate interaction patterns among users, locations, time, and activities, which is characterized by higher-order relations and heterogeneity. Recently, graph-based methods have gained popularity due to the advancements in graph neural networks. However, these methods encounter two significant challenges. Firstly, higher-order relations and heterogeneity are not adequately modeled. Secondly, the majority of established methods are designed around the static graph structures that rely solely on co-occurrence relations, which can be imprecise. To overcome these challenges, we propose DyHN, a dynamic heterogeneous hypergraph network for spatiotemporal activity prediction. Specifically, to enhance the capacity for modeling higher-order relations, hypergraphs are employed in lieu of graphs. Then we propose a set representation learning-inspired heterogeneous hyperedge learning module, which models higher-order relations and heterogeneity in spatiotemporal activity prediction using a non-decomposable manner. To improve the encoding of heterogeneous spatiotemporal activity hyperedges, a knowledge representation-regularized loss is introduced. Moreover, we present a hypergraph structure learning module to update the hypergraph structures dynamically. Our proposed DyHN model has been extensively tested on four real-world datasets, proving to outperform previous state-of-the-art methods by 5.98% to 27.13%. The effectiveness of all framework components is demonstrated through ablation experiments.