1. Web Ontology Language (OWL)

2. OWL The W3C Web Ontology Language (OWL) is a Semantic Web language designed to represent rich and complex knowledge about things, groups of things, and relations between things

3. Why not be inconsistent in at least one aspect of a language which is all about consistency? —Guus Schreiber, Why OWL and not WOL? the acronym OWL was proposed … as an easily pronounced acronym that would yield good logos, suggest wisdom...

4. OWL What is Ontology? Ontology is about the exact description of things and their relationships. For the web, ontology is about the exact description of web information and relationships between web information.

5. OWL is built on top of Resource Description Framework (RDF) OWL is written in XML OWL has three sub languages  OWL lite  OWL DL  OWL Full

6. Semantic Web Information is given explicit meaning XML provides a surface syntax for structured documents, but imposes no semantic constraints on the meaning of these documents. XML Schema is a language for restricting the structure of XML documents and also extends XML with datatypes.

7. Semantic Web RDF is a datamodel for objects ("resources") and relations between them, provides a simple semantics for this datamodel, and these datamodels can be represented in an XML syntax. RDF Schema is a vocabulary for describing properties and classes of RDF resources, with a semantics for generalization-hierarchies of such properties and classes.

8. Semantic Web OWL adds more vocabulary for describing properties and classes: among others, relations between classes (e.g. disjointness), cardinality (e.g. "exactly one"), equality, richer typing of properties, characteristics of properties (e.g. symmetry), and enumerated classes.

9. Semantic Web Information has meaning This information can be processed by computers Computers can use this information for many purposes

10. example An ontology describing families might include axioms stating that a "hasMother" property is only present between two individuals when "hasParent" is also present, and individuals of class "HasTypeOBlood" are never related via "hasParent" to members of the "HasTypeABBlood" class. If it is stated that the individual Harriet is related via "hasMother" to the individual Sue, and that Harriet is a member of the "HasTypeOBlood" class, then it can be inferred that Sue is not a member of "HasTypeABBlood".

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12. Citations Patel-Schneider, P. F. (2004, June). What is OWL (and why should I care)?. In KR (pp. 735-737). http://www.w3.org/2001/sw/wiki/OWL http://www.w3.org/TR/owl-features/