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Web Ontology Language: OWL - Vrije Universiteit Amsterdam

Web Ontology Language: OWL - Vrije Universiteit Amsterdam

Web Ontology Language: OWL - Vrije Universiteit Amsterdam

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14 Grigoris Antoniou and Frank van Harmelenor equivalently:We can also provide further details, such as:39Unlike typical database systems, <strong>OWL</strong> does not adopt the unique namesassumption, thus: just because two instances have a different name (or: ID),that does not imply that they are indeed different individuals. For example,if we state that each course is taught by at most one one staff member:and we subsequently state that a given course is taught by two staff members:this does not cause an <strong>OWL</strong> reasoner to flag an error. After all, the systemcould validly infer that the resources "949318" and "949352" are apparentlyequal. To ensure that different individuals are indeed recognised as such, wemust explicitly assert their inequality:Because such inequality statements occur frequently, and the requirednumber of such statements would explode if we wanted to state the inequalityof a large number of individuals, <strong>OWL</strong> provides a shorthand notation to assertthe pairwise inequality of all individuals in a given list:

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