Mapping Data to Ontologies with Exceptions Using Answer Set Programming
This work addresses a specific technical challenge in ontology-based data access for researchers in knowledge representation and databases, offering incremental improvements in mapping expressiveness and complexity analysis.
The paper tackles the problem of mapping relational databases to first-order ontologies in ontology-based data access by introducing an ASP-based framework for GLAV mappings with queries in rule bodies, showing it can express constraints and exceptions succinctly. It provides an algorithm for brave reasoning, proving data complexity is NP-complete or at least as hard as ontology query entailment, and reduces mapping programs to ∃-ASP for UCQ-rewritable queries.
In ontology-based data access, databases are connected to an ontology via mappings from queries over the database to queries over the ontology. In this paper, we consider mappings from relational databases to first-order ontologies, and define an ASP-based framework for GLAV mappings with queries over the ontology in the mapping rule bodies. We show that this type of mappings can be used to express constraints and exceptions, as well as being a powerful mechanism for succinctly representing OBDA mappings. We give an algorithm for brave reasoning in this setting, and show that this problem has either the same data complexity as ASP (NP- complete), or it is at least as hard as the complexity of checking entailment for the ontology queries. Furthermore, we show that for ontologies with UCQ-rewritable queries there exists a natural reduction from mapping programs to \exists-ASP, an extension of ASP with existential variables that itself admits a natural reduction to ASP.