First Order-Rewritability and Containment of Conjunctive Queries in Horn Description Logics

no code implementations • 19 Nov 2020 • Meghyn Bienvenu, Peter Hansen, Carsten Lutz, Frank Wolter

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 problems.

Computing FO-Rewritings in EL in Practice: from Atomic to Conjunctive Queries

no code implementations • 18 Apr 2018 • Peter Hansen, Carsten Lutz

A prominent approach to implementing ontology-mediated queries (OMQs) is to rewrite into a first-order query, which is then executed using a conventional SQL database system.