A Property Restriction can occur with Constants. For example one can define that Denigma is a Subset of everything that is managed by EVA. There one defines an Individual on a Role/Property by stating or giving the Individual that restricts this Role.
If one wants to put this in OWL one defines Denigma as an
owl:Class, then one says this is a SubClass of an
owl:Restriction. So the Subclass is linked to an Empty Node and the Empty Node is of the type
owl:Restriction which means that it is a Property Restriction which serves as a Class Constructor/Definition. There one says the Restriction is on the Property
isManagedBy. On does this with the OWL Vocabulary
owl:onProperty and then one states the Value, which is given as a Constant for this Restriction and one says
owl:hasValue and then one gives the Constant one has already defined previously, i.e. the Individual EVA.
Denigma ⊑ isManagedBy.(EVA)
:Denigma a owl:Class ; rdfs:subClassOf [ a owl:Restriction ; owl:onProperty :isManagedBy ; owl:hasValue: :EVA ] .
This is not the only way to restriction Properties
:AI a owl:Class . :Machine a owl:Class . :EVA a :AI . :isManagedby a owl:ObjectProperty ; rdfs:domain :Course ; rdfs:range :Person .