Local ambiguity and derived data update

A novel execution model for rule application in active databases is developed and applied to the problem of updating derived data in the context of semantic, object-based database models. The execution model is based on the use of “limited ambiguity rules” (LARs), which permit disjunction in rule actions. The execution model essentially performs a breadth-first exploration of alternative extensions of a user-proposed update, and returns all “completions” of that update, where a “completion” is defined to be an extension of a user-proposed update that satisfies a family of natural conditions (e.g., that no constraints are violated). Given a semantic, object-based database model schema, integrity constraints as well as specifications of derived classes and attributes are compiled into a family of LARs. A formal proof of the correctness of the system is described