Support dash:uniqueValueForClass

[hmottestad]

It's possible to model the concept of a key (unique identifier) in SHACL, but it's not possible to make the key local to subjects of a particular class.

Dash has the dash:uniqueValueForClass constraint that allows us to model that all ex:Person has to have a unique value for ex:uniqueID, but this value does not have to be unique for other classes, so ex:Cat can have overlapping values for ex:uniqueID.

It might be useful with other concepts of uniqueness based on some grouping. For instance it might be useful to say that a skos:Concept is unique based on the skos:definition within a a particular skos:ConceptScheme. This is not supported by dash:uniqueValueForClass.