Efficient Answering of k-Reachability on Temporal Bipartite Graphs

Zhuoqing Xu, Zhengyi Yang, Xiaoshuang Chen, Huangleshuai He, Xin Cao

Abstract: This paper investigates the k-reachability problem on temporal bipartite graphs, which determines whether a vertex can reach another vertex within a given time interval I and a step constraint k. The problem is motivated by real-world scenarios where the number of hops from a source vertex s to a target vertex t reflects the influence s exerts on t. Bipartite graphs are used to model relationships between two types of entities, such as people-location, author-paper, and customer-product. When modeling real-world applications like disease outbreaks, biomedical reactions, and travel planning, edges are often enriched with temporal information. Temporal bipartite graphs provide an effective tool for modeling these dynamic scenarios. Recent studies show that k-reachability on temporal bipartite graphs can expand research in the above fields. Adding a step constraint k provides more insights into the connectivity of temporal bipartite graphs. Although k-reachability has been extensively studied on unipartite graphs, it remains unexplored on temporal bipartite graphs. To fill this research gap, we propose an efficient algorithm for k-reachability problem on temporal bipartite graphs in this paper. Specifically, we introduce a 2-hop index-based approach to efficiently answer k-reachability queries. Extensive experiments on real-world datasets demonstrate that the proposed method achieves a speedup of at least three orders of magnitude in query performance.