rigoris Antoniou and Frank van Harmelen of the above <owl: ObjectProperty rdf ID="has <rdf: type rdf: resource="bon TransitiveProperty"/ ≤rdf:type <rdfs: domain rdf: resource=#student"/> Boolean combinations It is possible to talk about Boolean combinations(union, intersection,com- plement)of classes(be it defined by owl: Class or by class expressions). For example, we can say that courses and staff members are disjoint as follows <owl: Class rdf: about=#course"> <owl: Restriction> <owl: complementOf rdf: resource=#staffMember"/> </owl: Restriction> </rdfs: subClassOf This says that every course is an instance of the complement of staff members that is no course is a staff member. Note that this statement could also have been expressed using owl: disjointWith The union of classes is built using owl: unionof <owl: Class rdf: ID="peopleAtUni"> owl: unionOf rdf: parseType="Collection"> <owl: Class rdf: about=#staffMember"/ owl: Class rdf: about="#student"/ The rdf: parse Type attribute is a shorthand for an explicit syntax for building list with <rdf: first> and <rdf: rest> tags. Such lists are required because the built -in containers of rdf have a serious limitation there is no way to close them, i. e, to say "these are all the members of the container This is because, while one graph may describe some of the members, there is no way to exclude the possibility that there is another graph somewhere that describes additional members. The list syntax provides exactly this facility, but is very verbose, which motivates the rdf: parse Type shorthand notation Note that this does not say that the new class is a subclass of the union but rather that the new class is equal to the union. In other words, we have stated an equivalence of classes. Also, we did not specify that the two classes must be disjoint: it is possible that a staff member is also a student Intersection is stated with owl: intersectionOf12 Grigoris Antoniou and Frank van Harmelen An example of the syntactic form of the above is: <owl:ObjectProperty rdf:ID="hasSameGradeAs"> <rdf:type rdf:resource="&owl;TransitiveProperty" /> <rdf:type rdf:resource="&owl;SymmetricProperty" /> <rdfs:domain rdf:resource="#student" /> <rdfs:range rdf:resource="#student" /> </owl:ObjectProperty> Boolean combinations It is possible to talk about Boolean combinations (union, intersection, com￾plement) of classes (be it defined by owl:Class or by class expressions). For example, we can say that courses and staff members are disjoint as follows: <owl:Class rdf:about="#course"> <rdfs:subClassOf> <owl:Restriction> <owl:complementOf rdf:resource="#staffMember"/> </owl:Restriction> </rdfs:subClassOf> </owl:Class> This says that every course is an instance of the complement of staff members, that is, no course is a staff member. Note that this statement could also have been expressed using owl:disjointWith. The union of classes is built using owl:unionOf. <owl:Class rdf:ID="peopleAtUni"> <owl:unionOf rdf:parseType="Collection"> <owl:Class rdf:about="#staffMember"/> <owl:Class rdf:about="#student"/> </owl:unionOf> </owl:Class> The rdf:parseType attribute is a shorthand for an explicit syntax for building list with <rdf:first> and <rdf:rest> tags. Such lists are required because the built-in containers of RDF have a serious limitation: there is no way to close them, i.e., to say “these are all the members of the container”. This is because, while one graph may describe some of the members, there is no way to exclude the possibility that there is another graph somewhere that describes additional members. The list syntax provides exactly this facility, but is very verbose, which motivates the rdf:parseType shorthand notation. Note that this does not say that the new class is a subclass of the union, but rather that the new class is equal to the union. In other words, we have stated an equivalence of classes. Also, we did not specify that the two classes must be disjoint: it is possible that a staff member is also a student. Intersection is stated with owl:intersectionOf