332 Foundations of Semantic Web Technologies
8.5.6.2 SWI-Prolog
SWI-Prolog is another very popular open source Prolog system, developed
by Jan Wielemaker at the University of Amsterdam. It is available from
http://www.swi-prolog.org/.
8.5.6.3 Ontobroker
Ontobroker is a commercial logic programming system developed by onto-
prise GmbH, with a long history of ontology-based application development.
It supports reasoning with RIF, with F-Logic, but also with RDF and OWL,
and querying with SPARQL and conjunctive queries. Information is available
from http://www.ontoprise.de/en/home/products/ontobroker/.
8.5.6.4 DLV
DLV is a datalog system which is free for academic and non-commercial
use developed by the University of Calabria. It sports some extensions