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by throwaway290 987 days ago
> foo has a relationship with bar of type baz

Nope, "of type baz" is not required.

2 comments

Depends on the perspective. The predicate will always be an IRI. The object will either be an IRI or a literal, and all literals in RDF (as of RDF 1.1) are typed , though serialization formats like Turtle work with implied types.

There is also the option of blank nodes for objects, though in almost all implementations they are stand-ins for anonymous IRIs, so in some sense or another almost anything has "a" type.

God the word "type" is overloaded in common discourse. For a link

   ?s ?p ?o .
you could say this is a link of "type" ?p, but technically in RDF we say ?s is of type ?type if

   ?s <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> ?type .
which can be abbreviated as

   ?s a ?type .
If you have RDFS inference turned on, notably, just using ?p in a triple will imply

   ?p a rdf:Property .
In plain RDF you can say a property is of some other ?type but I think you can get in trouble with that if you want to do OWL DL inference and you might want to say something like

   ?p rdfs:subPropertyOf :SomeSpecialKindOfProperty .
if baz is meant to be relationship then I was low key wrong in my comment (I thought baz was the kind of bar, which can be untyped). But I guess the relationship must be a property at least