12 Dec. 2006CmpE 583 Fall 2006 Basic OWL Lite 1 Basic OWL Lite off Textbook Ch. 12: Classes & Properties Atilla Elçi

12 Dec. 2006CmpE 583 Fall 2006 Basic OWL Lite 2 Basic OWL Lite Involves class and property declarations. Class: –Represents domains in OWL –Subclass of rdfs:Class –Two kinds: Simple Named Classes Predefined Classes Property: –Associates values with individuals –By relating individuals to datatype or another individual –Can be a class to representing variety of property specification –Relates an instance of a domain to an instance of a range –There are four disjoint types of properties in OWL Lite: Datatype Object Annotation Ontology properties.

12 Dec. 2006CmpE 583 Fall 2006 Basic OWL Lite 3 Basic OWL Lite: Classes Simple Named Class (owl:Class): Classes are named using upper CamelCase User defines a simple named class as follows: or, may include class properties as well. rdf:ID signals that a new resource is being defined. Ref to a class: –Internally by URIRef fragment: #MyOntologyClass –Externally by full URIRef.

12 Dec. 2006CmpE 583 Fall 2006 Basic OWL Lite 4 Basic OWL Lite: Classes (continued) Predefined Classes (Extreme Classes): Thing Class (owl:Thing): –A super class for all classes Every individual is a member Every class is a subclass Everything about owl:Thing applies to everything! Can use typed node syntax: instead of rdf:resource=“URIRef” use Nothing Class (owl:Nothing): –Subclass of all classes –Empty class (has no individual members).

12 Dec Rev. 23/12/08 CmpE 583 Fall 2006 Basic OWL Lite 5 Basic OWL Lite: Properties There are four disjoint types of properties in OWL Lite: –Datatype –Object –Annotation –Ontology properties where “URI” is either: Each type is a subclass of rdf:Property Datatype Property (owl:DatatypeProperty) class: –Identifies a property whose value is associated with a datatype such as literal rather than resources. –For example, in defining sessionStartTime as a datatype property type: –The use of this property type: 8:30:00:00+01:00 –Compare that with the following: rdf:about=“...” 8:30:00+01:00

12 Dec. 2006CmpE 583 Fall 2006 Basic OWL Lite 6 Basic OWL Lite: Properties (continued) Object Properties (owl:ObjectProperty) class: –Identifies a property whose value is a reference to an individual (resource). –For example, in defining taughtBy as an object property: –The use of this property could be: Atilla Web Semantics 8:30:00+01:00

12 Dec. 2006CmpE 583 Fall 2006 Basic OWL Lite 7 Basic OWL Lite: Properties (continued) Annotation Properties (owl:AnnotationProperty) class: –Identifies a special type of property whose value is a named class, property, individual, or ontology. –For example, in defining annotation property on taughtBy (referred to as a URIRef): –There are predefined OWL annotation properties: rdfs:label rdfs:comment rdsf:seeAlso rdfs:isDefinedBy owl:versionInfo

12 Dec Rev. 23/12/08 CmpE 583 Fall 2006 Basic OWL Lite 8 Basic OWL Lite: Properties (continued) Ontology Properties (owl:OntologyProperty) class: –Identifies a type of property which relates to ontologies. –There are predefined OWL ontology properties: owl:imports owl:backwardCompatibleWith owl:incompatibleWith owl:priorVersion