is an Prolog library that provides complete support for querying
and processing OWL2
ontologies directly from within Prolog programs.
uses an SWI-Prolog's RDF
library for parsing and serializing ontologies, but the core model
is independent of RDF and is based on the OWL2 functional style
syntax, allowing direct manipulation of ontology axioms through
the Prolog database rather than indirectly via RDF triples.
previous versions of Thea (up until 0.5.5) provided a small number
of predicates to support the basic OWL entities - classes,
properties and individuals, Thea2 was redesigned to support OWL2
following precisely its structural syntax specification: every
axiom in the ontology would correspond on a one-to-one basis with
facts in the prolog database. This allows querying the Ontology by
simply query the prolog database using goals with variables as
has support from the Semantic Web Rule Language (SWRL). SWRL
antecedent-consequent rules are represented in the prolog database
as facts using a two-argument implies/2 predicate, rather than
directly as prolog rules. Thea also offers additional capabilities
including a bridge to the java OWL API and translation of
ontologies to Description Logic programs.
OWL Lib is
available under the GNU/GPL
documentation is available in SWI-Prolog's pldoc format
technical paper accepted in OWLED09.
- Mailing List
is open source and support is provided on a "best-effort"
basis by its developers . For any questions, comments and
suggestions please contact the mailing list: Thea-OWL-Lib