On Confluence Property of Active Databases with Meta-Rules

An active database consists of a collection of event-condition-action rules (or ECA-rules), some meta rules that specify the desired interactions and constraints for the execution of rable rules, and a traditional database. The main goal of an active database is to automatically manage database operations. In general, the occurrence of an event can cause several rules to be rable nondeterministically and the execution of a rable rule may dynamically cause some other rules to be rable. It is this nondeterministic and dynamical behavior that may result in more than one valid sequence of possible rule executions. In this paper we address the following problem in active database with metarules: Upon the occurrence of an event, whether, or under what conditions, one is guaranteed with a unique nal database state when the rule execution terminates. This property is called the connuence property. The main result is a suucient condition for an active database to be connuent. We show that under some reasonable assumptions this condition is also necessary for the connuence property.