Example 3: Qualities and quality values

Pattern 1: a literal value (Gemstone1's mass)

The simplest pattern: the quality is a reified individual, related to its bearer via a sub-property of gufo:inheresIn, and given a value via a sub-property of the datatype property gufo:hasQualityValue:

:Mass rdfs:subClassOf gufo:Quality .

:massOf rdfs:subPropertyOf gufo:inheresIn ;
    rdfs:domain :Mass ; rdfs:range :Gemstone .

:massInGrams rdfs:subPropertyOf gufo:hasQualityValue ;
    rdfs:domain :Mass ; rdfs:range xsd:double .

:Gemstone1Mass a :Mass ;
    :massOf :Gemstone1 ;
    :massInGrams "4.5"^^xsd:double .

The ontology also restricts :Mass to inhere in exactly one gemstone (owl:qualifiedCardinality "1" on gufo:inheresIn) -- a good habit for any quality type once its bearer's class is known, since gUFO itself leaves gufo:inheresIn unconstrained.

Use this pattern whenever a plain number (or string, date, ...) is all a quality value needs to be.

Pattern 2: an enumerated reified value (TShirt1's size)

A shirt size is not naturally a number: "S", "M", "L", "XL" is a closed, ordered set with no obvious numeric encoding worth committing to. Instead of a literal, the quality is given an individual drawn from a class of gufo:QualityValue, restricted by owl:oneOf to exactly those four individuals:

:ShirtSize rdfs:subClassOf gufo:QualityValue ;
    owl:equivalentClass [ a owl:Class ; owl:oneOf ( :S :M :L :XL ) ] .

:Size rdfs:subClassOf gufo:Quality .

:sizeOf rdfs:subPropertyOf gufo:inheresIn ;
    rdfs:domain :Size ; rdfs:range :TShirt .

:hasSizeValue rdfs:subPropertyOf gufo:hasReifiedQualityValue ;
    rdfs:domain :Size ; rdfs:range :ShirtSize .

:TShirt1Size a :Size ;
    :sizeOf :TShirt1 ;
    :hasSizeValue :M .

The object property gufo:hasReifiedQualityValue (rather than the datatype property gufo:hasQualityValue from pattern 1) is gUFO's marker that the value itself is a reified individual, not a literal.

Pattern 3: a multidimensional reified value (Painting1's color)

Color needs more than one number at once -- a point in a 3-D space, not a single scalar or an item from a closed list. The value is again a gufo:QualityValue individual (this time not restricted by owl:oneOf, since the space of RGB triples is not enumerable), but now it carries its own datatype properties, each a sub-property of gufo:hasValueComponent, one per dimension:

:ColorValueInRGB rdfs:subClassOf gufo:QualityValue .

:hasRedValueComponent rdfs:subPropertyOf gufo:hasValueComponent ;
    rdfs:domain :ColorValueInRGB ; rdfs:range xsd:nonNegativeInteger .
:hasGreenValueComponent rdfs:subPropertyOf gufo:hasValueComponent ; ... .
:hasBlueValueComponent  rdfs:subPropertyOf gufo:hasValueComponent ; ... .

:Color rdfs:subClassOf gufo:Quality .

:hasColorValueInRGB rdfs:subPropertyOf gufo:hasReifiedQualityValue ;
    rdfs:domain :Color ; rdfs:range :ColorValueInRGB .

:Painting1Color a :Color ;
    :colorOf :Painting1 ;
    :hasColorValueInRGB [ a :ColorValueInRGB ;
        :hasRedValueComponent "0"^^xsd:nonNegativeInteger ;
        :hasGreenValueComponent "47"^^xsd:nonNegativeInteger ;
        :hasBlueValueComponent "167"^^xsd:nonNegativeInteger ] .

Because the value is reified, the same color could, without touching :Painting1Color's identity, also be given a value in a different space -- e.g. a CMYK quadruple via a second hasColorValueInCMYK property -- something a bare literal could never support cleanly.