rigoris Antoniou and Frank van Harmelen <owl: Class rdf: about= #mathCourse <rdfs: subClass of> <owl: onProperty rdf: resource=#isTaughtBy"/> fowl: has Value rdf: resource=#949352"/> </owl: Restriction> </rdfs: subClassOf> </owl: Class> owl: has Value states a specific value that the property, specified by owl: on Property must have And we can declare that all academic staff members must teach at least one undergraduate course as follows <owl: Class rdf: about=#academicStaffMember> <owl: Restriction> rl: onProperty rdf: resource=#teaches"/> owl: someValuesFrom rdf: resource=#undergraduate Course"/> </owl: Restriction> </owl: Clas Let us compare owl: allValuesFrom and owl: some Values From The ex- ample using the former requires every person who teaches an instance of the class, a first year subject, to be a professor. In terms of logic we have a uni- versal quantification. The example using the latter requires that there erists an undergraduate course that is taught by an instance of the class, an academic staff member It is still possible that the same academic teaches postgraduate courses addition. In terms of logic we have an existential quantification. In general, a owl: Restriction element contains a owl: onProperty ele- ment, and one or more restriction declarations. One type of restriction decla- rations are those that define restrictions on the kinds of values the property an take wl: allValuesFrom, owl: has Value and owl: someValuesFrom. Another type are cardinality restrictions. Fo or exam ple, we can require every course to be taught by at least someone <ow: Class rdf: about=#course> <rdfs: subClassof> <ow⊥: Restriction> <owl: onProperty rdf: resource="#isTaughtBy"/> <owl: minCardinality rdf datatype="&xsd; nonNegativeInteger> </owl: minCardinality> </owl: Restriction> </rdfs: subClassOf> </owl: Class>10 Grigoris Antoniou and Frank van Harmelen <owl:Class rdf:about="#mathCourse"> <rdfs:subClassOf> <owl:Restriction> <owl:onProperty rdf:resource="#isTaughtBy"/> <owl:hasValue rdf:resource="#949352"/> </owl:Restriction> </rdfs:subClassOf> </owl:Class> owl:hasValue states a specific value that the property, specified by owl:onProperty must have. And we can declare that all academic staff members must teach at least one undergraduate course as follows: <owl:Class rdf:about="#academicStaffMember"> <rdfs:subClassOf> <owl:Restriction> <owl:onProperty rdf:resource="#teaches"/> <owl:someValuesFrom rdf:resource="#undergraduateCourse"/> </owl:Restriction> </rdfs:subClassOf> </owl:Class> Let us compare owl:allValuesFrom and owl:someValuesFrom. The ex￾ample using the former requires every person who teaches an instance of the class, a first year subject, to be a professor. In terms of logic we have a uni￾versal quantification. The example using the latter requires that there exists an undergraduate course that is taught by an instance of the class, an academic staff member. It is still possible that the same academic teaches postgraduate courses, in addition. In terms of logic we have an existential quantification. In general, a owl:Restriction element contains a owl:onProperty ele￾ment, and one or more restriction declarations. One type of restriction decla￾rations are those that define restrictions on the kinds of values the property can take: owl:allValuesFrom, owl:hasValue and owl:someValuesFrom. Another type are cardinality restrictions. For example, we can require every course to be taught by at least someone. <owl:Class rdf:about="#course"> <rdfs:subClassOf> <owl:Restriction> <owl:onProperty rdf:resource="#isTaughtBy"/> <owl:minCardinality rdf:datatype="&xsd;nonNegativeInteger"> 1 </owl:minCardinality> </owl:Restriction> </rdfs:subClassOf> </owl:Class>