@prefix ex: <http://example.org/iadopt/challenge/> .
@prefix iop: <https://w3id.org/iadopt/ont/> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .

ex:pH a iop:Variable ;
    rdfs:label "pH measurement of a liquid sample solution" ;
    rdfs:comment "solution hydronium ion activity" ;
    iop:hasConstraint [
      a iop:Constraint ;
      rdfs:label "thermodynamic temperature (optional)" ;
      iop:constrains ex:Prop
    ] ;
    iop:hasMatrix ex:Matrix ;
    iop:hasObjectOfInterest ex:OoI ;
    iop:hasProperty ex:Prop .

ex:Matrix
    a iop:Entity, iop:System ;
    rdfs:label "homogeneous solution" .

ex:OoI
    a iop:Entity ;
    rdfs:label "all hydronium contributing species (acids)" .

ex:Prop
    a iop:Property ;
    rdfs:label "pH" .