proposal: a reifier should reify only one "thing"

Hi all,

after writing my response to Phil [1], which is a refinement of the 
arguments I made last Friday [2], I'm more and more convinced that a 
reifier should not reify several things, because it would lead to wrong 
expectations ("this is similar to a named graph, right?") and 
counter-intuitive inferences (again, see my example in [1]).

That being said, I would have this constraint /only/ expressed  the 
"intended meaning" of the rdf:reifies predicate -- in a way very similar 
to rdf:subject, rdf:predicate and rdf:object. Reading the description of 
these predicate in [3] strongly hints at the fact that they are supposed 
to have only one value each ("[rdf:subject] is used to state *the* 
subject of a statement"), but

* it is not enforced syntactically (the following is valid RDF: :t 
rdf:object :s1, :s2. ),
* it is not enforced semantically (the example above does not entail :s1 
owl:sameAs :s2 ).

The arguments against such an enforcement (syntactic or semantic) have 
been largely discussed already, I won't repeat them here.


Finally, I want to emphasize that, although I advocate that a reifier 
should reify only one thing, I would like to remain very vague on what 
kind of "thing" that is, and how many (syntactically) distinct triples 
would actually identity that thing.

For example, from the following graph

     :r rdf:reifies
         <<( dbr:Linköping dbo:populationTotal 104232 )>>.

it would seem appropriate to infer (under D-entailment where xsd:integer 
∈ D)

     :r rdf:reifies
         <<( dbr:Linköping dbo:populationTotal 104232 )>>,
         <<( dbr:Linköping dbo:populationTotal 00104232 )>>.

(I believe that it would be the case with the semantics currently 
proposed by Enrico).

 From the following graph

     :r rdf:reifies
         <<( :alice :knows :bob )>>.
     :knows a owl:SymetricProperty.

MAYBE it would be appropriate to infer

     :r rdf:reifies
         <<( :alice :knows :bob )>>,
         <<( :bob :knows :alice )>>.

 From the following graph

     :r rdf:reifies
         <<( :alice :worksWith :bob )>>.
     :worksWith rdfs:subPropertyOf :knows.

MAYBE it would be appropriate to infer

     :r rdf:reifies
         <<( :alice :worksWith :bob )>>,
         <<( :alice :knows :bob )>>.

I don't have a definite answer for the two examples above, and I don't 
think that we need to answer them urgently. I'm just pointing out that 
we have some leeway even if we settle on "a reifier reifies only one thing".

   pa

[1] https://www.w3.org/mid/d39fcb64-66d6-4cbe-9453-a52d1cbd5259@w3.org

[2] https://www.w3.org/2024/04/12-rdf-star-minutes.html#x169

[3] https://www.w3.org/TR/rdf11-schema/#h3_ch_reificationvocab