OWL Ontology: Represent increasing number, like first, second, third

I have a question about an OWL ontology that I am making. I have a class that is actually an ID class and I would li开发者_JS百科ke to have instances: first, second, third etc.

The first solution that I have figured is creating individuals {first, second, third etc} for this class, but then I have to write a huge number of individuals.

The other solution is to create a data property that will be connected with my class that has type "integer".

The second solution looks more appropriate but the thing is that I can't represent the word "first", just the number 1.

Do you know how I can do that?

You could create a class of ordinals that are uniquely identified by an integer, like so (in Turtle syntax):

:hasPosition  a  owl:DatatypeProperty, owl:FunctionalProperty ;
    rdfs:range  xsd:integer .
:Ordinal  a  owl:Class ;
    rdfs:subClassOf  [
        a  owl:Restriction ;
        owl:onProperty  :hasPosition ;
        owl:someValuesFrom  :integer
    ] ;
    owl:hasKey ( :hasPosition ) .

Note the use of owl:hasKey (introduced in OWL 2) which means that the value of :hasPosition identifies a unique instance. The property is functional so that an instance cannot have two distinct positions.