Web Ontology Language (OWL)

Web Ontology Language (OWL) is a core world wide web consortium [W3C] standard Knowledge representation language for the Semantic Web. The term Knowledge representation in general refers to the method of modeling the knowledge about the real world entities and relations. OWL is a highly expressive, flexible and efficient knowledge representation language, that can be used to model background knowledge about domains e.g. Health care, Social Network, Automobiles. OWL is derived from a well known family of logics called Description Logics (DLs) [Baader, 2007], and therefore, offers a well-defined semantics to the language. A key advantage of using OWL and other logic based modeling languages is that these languages support many reasoning services. Reasoning is a method of processing background (explicit) knowledge and infer implicit information. E.g. consider the statements, every Father is a Male and Alex is a Father, then an OWL reasoner can reason with this knowledge and infer that Alex is a Male. OWL semantics supports the open world assumption (OWA), that follows the notion that knowledge about the world at any point of time is incomplete, in other words things that are not known to be true are not necessarily false. OWA is suitable for applications on the world wide web setting where the information is ever increasing. The current version of OWL called OWL 2, became a W3C standard in 2009, it is more expressive than its predecessor OWL 1 (2004). [Motik, 2009] provides more information about the differences between OWL 1 and OWL 2 versions. The following section presents an overview of the OWL 2 syntax.