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".





Received on Wednesday, 17 April 2024 23:18:30 UTC