OWL

From ONTORULE Show Case

The Web Ontology Language OWL is an ontology language for the Semantic Web that extends RDF Schema and is based on Description Logics. To RDF Schema it adds features such as class intersection, union and complement, local property restrictions, cardinality restrictions, and reflexive, symmetric, functional, transitive and inverse properties.

Version 1 of OWL became a recommendation in 2004. It consists of 3 species: OWL Full is the most expressive, it contains all OWL 1 language constructs, and allows writing arbitrary RDF graphs, but reasoning is not decidable; OWL DL is based on the Description Logic SHOIN, it contains all OWL 1 language constructs, but restricts the shape of RDF graphs to retain decidability; OWL Lite is a restriction of OWL DL that does not allow the use of nominals (i.e., individuals in class descriptions) and cardinalities of arity higher than 1.

OWL 2 became a recommendation in 2009. OWL 2 DL is based on the Description Logic SROIQ; it extends OWL 1 DL with such things as property chains, keys, and qualified cardinality restrictions. OWL 2 Full includes all OWL 2 language constructs and allows writing arbitrary RDF graphs. OWL 2 features three language profiles, which are all subsets of OWL 2 DL and are all optimized for efficient processing: OWL 2 EL is suitable for ontologies with large numbers of classes, OWL 2 QL is suitable for querying ontologies with large data sets, and OWL 2 RL is amenable to rule processing; i.e., a standard forward chaining rule reasoner can be used for reasoning with OWL 2 RL ontologies.