Re: voting against use of rdf:ReificationProperty

On 1 Sep 2024, at 23:09, Gregory Williams <greg@evilfunhouse.com> wrote:

I’m not sure I follow the reasoning here, and perhaps I’ve been too terse in my example in previous messages. When you say "in a different standardised context,” what do you mean? I’m imagining a case where somebody wants to use RDF 1.0-style reification because they want to specifically make "statements about statements”. If they were to to model two different statements using the existing vocabulary for reification, they might get something like this:

# original two statements
<s> <p> “o” .
<x> <y> <<( <a> <b> <c> )>> .

# reification of those statements
_:a a rdf:Statement .
_:a rdf:subject <s> .
_:a rdf:predicate <p> .
_:a rdf:object "o" .

_:b a rdf:Statement .
_:b rdf:subject <x> .
_:b rdf:predicate <y> .
_:b rdf:object <<( <a> <b> <c> )>> .

# whatever "statements about those statements" the user wanted:
_:a <q> "some annotation" .
_:b <q> "some other annotation" .

I think this is perfectly reasonable, and I’m trying to understand what the reificationProperty proposal means for this example (or what value it brings). We would see that in this case `rdf:object rdf:type rdf:reificationProperty` (in addition to other entailments), and I’m not sure what (if any) impact that might have on the rest of the data.

OK,I guess that I now see where do you come from.
So, If I understand well, your issue is somehow about backward compatibility.
Namely: what happens to graphs using perfectly valid “old-style” reification together with RDF-star style reification (according to <https://github.com/w3c/rdf-star-wg/wiki/RDF-star-%22alternative-baseline%22>)?
In the example above, there will be the entailments:
rdf:object a rdf:reificationProperty.
<y> a rdf:reificationProperty.

I don’t think there is any "mistake in their model” here, which suggests to me that at least in some cases it is reasonable to have a property whose range includes both triple terms *and* non-triple terms. I’m interested here less in whether “both cases are fine,” and more in whether “both cases AT THE SAME TIME are fine” (and therefore whether it’s even right to talk about “WHICH one makes sense in their context”).

Note that the above happens only when you MIX old style reification with RDF-star style reification in the same graph.
That is, you use old style reification (with rdf:object) for a triple which contains a triple term (which cannot happen in RDF-1.1).
Clearly, you get bizzarre consequences, IMHO.
So, we need to state in the documentation of RDF-star that it is not advisable to use old style reification together with RDF-star style reification in the same graph - a perfectly reasonable request, I guess.

cheers
—e.