Logical Aspects of Events: Quantification, Sorts, Composition and Disjointness

An event, as opposed to an atemporal property, has its own time and location and occurs once. Although the notion of events has been found in researches on ontology, logic, linguistics, artificial intelligence and deductive databases, the different approaches to this notion do not seem to capture the various logical aspects of events. This paper proposes an event logic with expressions such as quantification over events, event sort-hierarchy, and composition and disjointness of events. In the logic, events are regarded as constants, sorts, predicates and variables in an order-sorted second-order language, which provides knowledge representation and reasoning for event assertions. In order to implement a query answering system, we present a sorted tableau calculus for the refutation of event formulas in logic.