Core iCODA technology on efficiently querying heterogeneous data sources through RDFS ontologies to be presented next week (June 2-6) at the European Semantic Web Conference in Portoroz. A joint work of the CEDAR and GraphIK teams illustrating the cooperation between databases and knowledge engineering. Check the preprint on HAL.
Abstract. Query answering in RDF knowledge bases has traditionally been performed either through graph saturation, i.e., adding all implicit triples to the graph, or through query reformulation, i.e., modifying the query to look for the explicit triples entailing precisely what the original query asks for. The most expressive fragment of RDF for which Reformulation-based quey answering exists is the so-called database fragment, in which implicit triples are restricted to those entailed using an RDFS ontology. Within this fragment, query answering was so far limited to the interrogation of data triples (non-RDFS ones); however, a powerful feature specific to RDF is the ability to query data and schema triples together. In this paper, we address the general query answering problem by reducing it, through a pre-query reformulation step, to that solved by the query reformulation technique of . We also report on experiments demonstrating the low cost of our reformulation algorithm.