Description logics (DLs) have a long tradition in computer science and knowledge
representation, being designed so that domain knowledge can be described and so that …

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 …

Incomplete data, in the form of null values, has been extensively studied since the inception
of the relational model in the 1970s. Anecdotally, one hears that the way in which SQL, the …

An important issue that arises when querying description logic (DL) knowledge bases is how
to handle the case in which the knowledge base is inconsistent. Indeed, while it may be …

We study FO-rewritability of conjunctive queries in the presence of ontologies formulated in
a description logic between EL and Horn-SHIF, along with related query containment …

We introduce metric temporal description logics (mTDLs) as combinations of the classical
description logic ALC with (a) LTL bin, an extension of the temporal logic LTL with succinctly …

Ontology-mediated query answering (OMQA) is a new paradigm in data management that
seeks to exploit the semantic knowledge expressed in ontologies to improve query …

We introduce the query-by-example (QBE) paradigm for query answering in the presence of
ontologies. Intuitively, QBE permits non-expert users to explore the data by providing …

State constraints in AI Planning globally restrict the legal environment states. Standard
planning languages make closed-domain and closed-world assumptions. Here we address …

Handling incomplete data in a correct manner is a notoriously hard problem in databases.
Theoretical approaches rely on the computationally hard notion of certain answers, while …