What is Event Knowledge Graph: A Survey

Besides entity-centric knowledge, usually organized as Knowledge Graph (KG), events are also an essential kind of knowledge in the world, which trigger spring up event-centric representation form like Event KG (EKG). It plays increasingly important role many downstream applications, such search, question-answering, recommendation, financial quantitative investments, and text generation. This paper provides a comprehensive survey EKG from history, ontology, instance, application views. Specifically, to characterize thoroughly, we focus on its definitions, schema induction, acquisition, related representative graphs/systems, applications. The development processes trends studied therein. We further summarize prospective directions facilitate future research EKG.