We present the framework of ontology-based data access, a semantic paradigm for
providing a convenient and user-friendly access to data repositories, which has been …

Abstract Information systems have to deal with an increasing amount of data that is
heterogeneous, unstructured, or incomplete. In order to align and complete data, systems …

This paper is a survey of the research topics in the field of Semantic Web, Linked Data and
Web of Data. This study looks at the contributions of this research community over its first …

We present the architecture and technologies underpinning the OBDA system Ontop and
taking full advantage of storing data in relational databases. We discuss the theoretical …

Recent years have seen an increasing interest in ontology-mediated query answering, in
which the semantic knowledge provided by an ontology is exploited when querying data …

We present an extension of the ontology-based data access platform Ontop that supports
answering SPARQL queries under the OWL 2 QL direct semantics entailment regime for …

This paper presents Graal, a java toolkit dedicated to ontological query answering in the
framework of existential rules. We consider knowledge bases composed of data and an …

Recently several inconsistency-tolerant semantics have been introduced for querying
inconsistent description logic knowledge bases. Most of these semantics rely on the notion …

We give a solution to the succinctness problem for the size of first-order rewritings of
conjunctive queries in ontology-based data access with ontology languages such as OWL 2 …

Given a source relational database, a target OWL ontology and a mapping from the source
database to the target ontology, Ontology-Based Data Access (OBDA) concerns answering …