Temporal Enrichment and Querying of Ontology-Compliant Data

Abstract

We consider the problem of answering temporal queries on RDF stores, in presence of time-agnostic RDFS domain ontologies, of relational data sources that include temporal information, and of rules that map the domain information in the source schemas into the target ontology. Our proposed solution consists of two rule-based domainindependent algorithms. The first algorithm materializes target RDF data via a version of data exchange that enriches both the data and the ontology with temporal information from the relational sources. The second algorithm accepts as inputs temporal queries expressed in terms of the domain ontology, using SPARQL supplemented with a lightweight easy-to-use formalism for time annotations and comparisons. The algorithm translates the queries into the standard SPARQL form that respects the structure of the temporal RDF information while preserving the semantics of the questions, thus ensuring successful evaluation of the queries on the materialized temporally-enriched RDF data. In this paper we present the algorithms, report on their implementation and experimental results for two application domains, and discuss future work.