Mapping Analysis in Ontology-Based Data Access: Algorithms and Complexity

Ontology-based data access (OBDA) is a recent paradigm for accessing data sources through an ontology that acts as a conceptual, integrated view of the data, and declarative mappings that connect the ontology to the data sources. We study the formal analysis of mappings in OBDA. Specifically, we focus on the problem of identifying mapping inconsistency and redundancy, two of the most important anomalies for mappings in OBDA. We consider a wide range of ontology languages that comprises OWL 2 and all its profiles, and examine mapping languages of different expressiveness over relational databases. We provide algorithms and establish tight complexity bounds for the decision problems associated with mapping inconsistency and redundancy. Our results prove that, in our general framework, such forms of mapping analysis enjoy nice computational properties, in the sense that they are not harder than standard reasoning tasks over the ontology or over the relational database schema.