Constrain value of property to a single value?

Question

I would like to have a date property that can have any individual as is subject (i.e., there is no restriction on the domain), but can only have the value 1 (double) as a value. Is there a restriction suitable for this use case? Perhaps exact or value? I am using Protege.

Answer 1

You can just specify the range of the property as an enumerated class. In Protege, you'd write it as:

    { 1.0 }

The resulting ontology, in Turtle and RDF/XML:

@prefix :      <http://example.org/> .
@prefix rdf:   <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix owl:   <http://www.w3.org/2002/07/owl#> .
@prefix xsd:   <http://www.w3.org/2001/XMLSchema#> .
@prefix rdfs:  <http://www.w3.org/2000/01/rdf-schema#> .

:p      a           owl:DatatypeProperty ;
        rdfs:range  [ a          rdfs:Datatype ;
                      owl:oneOf  [ a          rdf:List ;
                                   rdf:first  1.0 ;
                                   rdf:rest   ()

                                 ]
                    ] .

:       a       owl:Ontology .

<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns="http://example.org/"
    xmlns:owl="http://www.w3.org/2002/07/owl#"
    xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
    xmlns:xsd="http://www.w3.org/2001/XMLSchema#">
  <owl:Ontology rdf:about="http://example.org/"/>
  <owl:DatatypeProperty rdf:about="http://example.org/p">
    <rdfs:range>
      <rdfs:Datatype>
        <owl:oneOf>
          <rdf:List>
            <rdf:first rdf:datatype="http://www.w3.org/2001/XMLSchema#decimal"
            >1.0</rdf:first>
            <rdf:rest rdf:resource="http://www.w3.org/1999/02/22-rdf-syntax-ns#nil"/>
          </rdf:List>
        </owl:oneOf>
      </rdfs:Datatype>
    </rdfs:range>
  </owl:DatatypeProperty>
</rdf:RDF>

If you want the datatype to be xsd:double rather than xsd:decimal, you just specify the range as {"1.0"^^double} instead: