Ricerc@Sapienza

The Semantic Web is commonly interpreted under the open-world assumption meaning that information available (e.g., in a data source) only captures a subset of the reality. Therefore, there is no certainty about whether the available information provides a complete representation of the reality. The broad aim of this paper is to contribute a formal study of how to describe the completeness of parts of the Semantic Web stored in RDF data sources. We introduce a theoretical framework allowing to augment RDF data sources with statements, also expressed in RDF, about their completeness.

OWL2QL is the profile of OWL2 targeted to Ontology-Based Data Access (OBDA) scenarios, where large amount of data are to be accessed, and thus answering conjunctive queries over data is the main task. However, this task is quite restrained wrt the classical KR Ask-and-Tell framework based on query- ing the whole theory, not only facts (data). If we use SPARQL as query language, we get much closer to this ideal.