How to represent maps in OWL? - owl

Question

This is a simplified extract from my ontology:
<owl:Class rdf:ID="Role" />
<owl:Class rdf:ID="Location" />
<owl:Class rdf:ID="SalaryRange">
<rdfs:subClassOf rdf:resource="#HasLocation" />
</owl:Class>
<owl:Class rdf:ID="HasLocation" />
<owl:ObjectProperty rdf:ID="location">
<rdfs:domain rdf:resource="#HasLocation" />
<rdfs:range rdf:resource="#Location" />
</owl:ObjectProperty>
<owl:DataProperty rdf:ID="salaryRangeOfRole">
<rdfs:domain rdf:resource="#Role" />
<rdfs:range rdf:resource="#SalaryRange" />
</owl:DataProperty>
How can I ensure now that the Locations in the SalaryRanges are unique per Role?
I have read about FunctionalPropertys, but do not see how to use this in this case.

Answer 1

The challenge you have here is that you basically want a unique constraint on Role and Location for SalaryRange. Funtional properties really is defined for a single property - except if you do model some functional property through class expressions.
A simple way to achieve this (if you are using OWL) is through key constraints. I battle a bit to understand your example. I therefore simplified your example further to assuming you have a SalaryRange for which the Role and Location need to be unique. I think if you understand the general idea you will be able to modified it to fit your example exactly.
We have the classes Location and Role as you defined it.
<owl:Class rdf:about="Location"/>
<owl:Class rdf:about="Role"/>
Then I defined object properties role and location follows:
<owl:ObjectProperty rdf:about="location">
<rdfs:domain rdf:resource="SalaryRange"/>
<rdfs:range rdf:resource="Location"/>
</owl:ObjectProperty>
<owl:ObjectProperty rdf:about="role">
<rdfs:domain rdf:resource="SalaryRange"/>
<rdfs:range rdf:resource="Role"/>
</owl:ObjectProperty>
Then to ensure that SalaryRange will have unique roles and locations, you can enforce it as follows:
<owl:Class rdf:about="SalaryRange">
<owl:hasKey rdf:parseType="Collection">
<rdf:Description rdf:about="location"/>
<rdf:Description rdf:about="role"/>
</owl:hasKey>
</owl:Class>
You can test this with the following individuals:
<owl:NamedIndividual rdf:about="location1">
<owl:sameAs rdf:resource="location2"/>
</owl:NamedIndividual>
<owl:NamedIndividual rdf:about="location2"/>
<owl:NamedIndividual rdf:about="role1">
<owl:sameAs rdf:resource="role2"/>
</owl:NamedIndividual>
<owl:NamedIndividual rdf:about="role2"/>
<owl:NamedIndividual rdf:about="salaryRange1">
<location rdf:resource="location1"/>
<role rdf:resource="role1"/>
</owl:NamedIndividual>
<owl:NamedIndividual rdf:about="salaryRange2">
<location rdf:resource="location2"/>
<role rdf:resource="role2"/>
</owl:NamedIndividual>
With these individuals a reasoner like Hermit will infer that salaryRange1 and salaryRange2 are the same individual. However, if you state that salaryRange1 and salaryRange2 are different individuals, you will get an inconsistency.
<rdf:Description>
<rdf:type rdf:resource="http://www.w3.org/2002/07/owl#AllDifferent"/>
<owl:distinctMembers rdf:parseType="Collection">
<rdf:Description rdf:about="salaryRange1"/>
<rdf:Description rdf:about="salaryRange2"/>
</owl:distinctMembers>
</rdf:Description>
To resolve the inconsistency you can state that either role1 and role2 are different individuals OR location1 and location2 are different individuals.