Abstractions of Queries in Ontology-Based Data Access

This article addresses query abstraction in ontology-based data access (OBDA) by translating data queries to the ontology layer using existential rules and certain answer semantics.

• Introduces minimally complete and maximally sound abstractions to handle cases where perfect abstraction is unavailable.
• Studies abstractions within an extension of UCQs featuring limited inequality and a special predicate for database constants.
• Demonstrates that this extension maintains problem complexity while expressing minimally complete abstractions.
• Characterizes maximally sound abstractions by linking them to the notion of maximum recovery from data exchange.