Answering Ontological Ranking Queries based on Subjective Reports

The use of preferences in query answering, both in traditional databases and in ontology-based data access, has recently received much attention, due to its many real-world applications. In this paper, we tackle the problem of query answering in Datalog+/− ontologies subject to the querying user's preferences and a collection of subjective reports (i.e., scores for a list of features) of other users, who have their own preferences as well. All these pieces of information are combined to rank the query results. We first propose a basic approach to deal with Datalog+/− ontologies without directly addressing query answering. Then, we extend our approach to deal with query answering using provenance information