A Knowledge-Level View of Consistent Query Answers
Eric Evangelista · Summit (Simon Fraser University) · 2004
Of the numerous formal approaches that deal with database inconsistencies with respect to integrity constraints, all share the view that such constraints are statements about the world the database models.An alternative perspective, however, considers constraints as statements about the knowledge the database has of its domain.The result of this shift in perspective allows us to regard integrity constraint violations as a fragment of the incomplete knowledge the system has of the world.We can then query the possibly inconsistent database for consistent query answers.We address the above considerations with an epistemic query language KC, where the possible ways to repair a database that violates its integrity constraints are characterized by a set of possible worlds, an epistemic state e c .This culminates in a situation where only