Ontology-based data access is concerned with querying incomplete data sources in the
presence of domain-specific knowledge provided by an ontology. A central notion in this …

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 …

While big data analytics is considered as one of the most important paths to competitive
advantage of today's enterprises, data scientists spend a comparatively large amount of time …

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 …

Abstract Query answering over Description Logic (DL) ontologies has become a vibrant field
of research. Efficient realizations often exploit database technology and rewrite a given …

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 …

RDF Database Systems is a cutting-edge guide that distills everything you need to know to
effectively use or design an RDF database. This book starts with the basics of linked open …

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 …

Current techniques for query answering over DL-Lite ontologies have severe limitations in
practice, since they either produce complex queries that are inefficient during execution, or …

Ontological queries are evaluated against a knowledge base consisting of an extensional
database and an ontology (ie, a set of logical assertions and constraints that derive new …