Basic OWL Lite off Textbook Ch. 12: Classes & Properties

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

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. CmpE 583 Fall 2006

3. Basic OWL Lite: Classes Simple Named Class (owl:Class): • Classes are named using upper CamelCase • User defines a simple named class as follows: <owl:Class rdf:ID=“MyOntologyClass”/> 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. CmpE 583 Fall 2006

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 <rdf:Thing rdf:about=“URIRef” /> • Nothing Class (owl:Nothing): • Subclass of all classes • Empty class (has no individual members). CmpE 583 Fall 2006

5. Basic OWL Lite: Properties There are four disjoint types of properties in OWL Lite: • Datatype • Object • Annotation • Ontology properties <owl:Ontology rdf:about=“URI”> 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: <owl:DatatypeProperty rdf:ID=“sessionStartTime”> <rdfs:domain rdf:resource=“#Lecture” /> <rdfs:range rdf:resource=“&xsd;time”> </owl:DatatypeProperty> • The use of this property type: <sessionStartTime rdf:datatype=“&xsd;time”>8:30:00:00+01:00</session...> • Compare that with the following: rdf:about=“...” <train:Lecture rdf:ID=“CmpE583”> <startTime>8:30:00+01:00</startTime> </train:Lecture> CmpE 583 Fall 2006

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: <owl:ObjectProperty rdf:ID=“taughtBy”/> • The use of this property could be: <Person rdf:ID=“aelci”> <givenName>Atilla</givenName> </Person> <train:Lecture rdf:ID=“CmpE583”> <rdfs:label>Web Semantics</rdfs:label > <startTime>8:30:00+01:00</startTime > <taughtBy rdf:resource=“#aelci” /> </train:Lecture> CmpE 583 Fall 2006

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): <owl:AnnotationProperty rdf:about=“#taughtBy” > <propertyX .... /> <propertyY .... /> </owl:AnnotationProperty> • There are predefined OWL annotation properties: • rdfs:label • rdfs:comment • rdsf:seeAlso • rdfs:isDefinedBy • owl:versionInfo CmpE 583 Fall 2006

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 CmpE 583 Fall 2006