On confluence property of active databases with meta-rules

Abstract

An active database consists of a collection of event-conditionaction rules (or ECA-rules), some meta rules that specify the desired interactions and constraints for the execution of finable 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 firable nondeterministically and the execution of a firable rule may dynamically cause some other rules to be firable. 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 meta-rules: Upon the occurrence of an event, whether, or under what conditions, one is guaranteed with a unique final database state when the rule execution terminates. This property is called the confluence property. The main result is a sufficient condition for an active database to be confluent. We show that under some reasonable assumptions this condition is also necessary for the confluence property.