In recent years, we have witnessed a revival of the use of recursive queries in a variety of
emerging application domains such as data integration and exchange, information …

We study fundamental aspects related to the efficient processing of the SPARQL query
language for RDF, proposed by the W3C to encode machine-readable information in the …

The modern enterprise software stack—a collection of applications supporting bookkeeping,
analytics, planning, and forecasting for enterprise data—is in danger of collapsing under its …

This paper summarizes results on a recently introduced family of Datalog-based languages,
called Datalog+/-, which is a new framework for tractable ontology querying, and for a variety …

Answering conjunctive queries (CQs) over a set of facts extended with existential rules is a
prominent problem in knowledge representation and databases. This problem can be …

Datalog∃ is the extension of Datalog, allowing existentially quantified variables in rule
heads. This language is highly expressive and enables easy and powerful knowledge …

The initial and basic role of the chase procedure was to test logical implication between sets
of dependencies in order to determine equivalence of database instances known to satisfy a …

A lot of research activity has recently taken place around the chase procedure, due to its
usefulness in data integration, data exchange, query optimization, peer data exchange and …

The chase has become a staple of modern database theory with applications in data
integration, query optimisation, data exchange, ontology-based query answering, and many …

We show that all–instances termination of chase is undecidable. More precisely, there is no
algorithm deciding, for a given set \calT consisting of Tuple Generating Dependencies (aka …