Re: a modest proposal - eliminate reifiers completely

Sorry, I wasn't aware of the changed syntax.

# syntax expansion.
_:b rdf:reifies <<( :s :p :o )>> .
_:b :p1 :o1.
_:b :p2 :o2 .

is fine.

*Kurt Cagle*
Editor in Chief
The Cagle Report
kurt.cagle@gmail.com
443-837-8725 <http://voice.google.com/calls?a=nc,%2B14438378725>


On Sun, Apr 14, 2024 at 1:35 PM Andy Seaborne <andy@apache.org> wrote:

>
>
> On 12/04/2024 20:40, Kurt Cagle wrote:
> ...
> > I was at an IA conference yesterday, and the question of reification was
> > raised in several different contexts. I think it's important to remember
> > that reification is significant primarily because it is accommodating
> > (syntactically) parity with a neo4j construct.
> >
> > That is to say:
> >
> > :s :p :o .
> > :s  a  rdf:type .
> > << :s :p :o >> :p1 :o1; :p2 :o2 .
>
> :s :p :o .
> :s  a  rdf:type .
> # syntax expansion.
> _:b rdf:reifies <<( :s :p :o )>> .
> _:b :p1 :o1.
> _:b :p2 :o2 .
>
> >
> > is the equivalent of a neo4j assertion with two properties on its "edge".
> >
> >
> > What I see here is that we're also attempting to create an assignment
> > statement with reifiers in Turtle:
> >
> > <<(:r | :s :p :o )>>
>
> Is that proposal to have named triples?
>
> Or was that the syntax
>
>     << :r | :s :p :o >>
>
> ?
>
>
> A second << :r1 | :s :p :o >> "assigns" :r1 as a different name for tjhe
> occurrence.
>
> In words, an occurrence (usage) named :r, and one name :r1, of the
> triple :s :p :o (there is at most one triple :s :p :o ).
>
> An edge is more like an occurrence - a usage of a triple. Multiple edges
> are multiple occurrences each of which can have different annotations.
>
> (The triple occurrence / triple type language has slipped a bit.)
>
> > when this is an operation that is normally done in SPARQL:
> >
> > bind (<<:s :p :o>> as ?r)
>
> That could be:
>
>      bind (<<( :s :p :o )>> as ?tripleTerm)
>
> Binding the triple term -- all <<( :s :p :o )>> are the same RDF term.
>  From a triple term, you can get the subject.
>
>     SUBJECT(?tripleTerm) --> :s
>
> For the forms
>
>     bind (<< :s :p :o >> as ?r)
>     bind (<< :e | :s :p :o >> as ?r)
>
> <<:s :p :o>> isn't an RDF term. This BIND form would have a side effect
> of making a blank node or URI :e and assigning it to ?r.
>
> But there is no way to get back from ?r to the parts of ":s :p :o" --
> SUBJECT(?r) doesn't work (unless we have "special" bnodes and URIs!).
>
> Having it as a triple
>
>      _:b rdf:reifies <<( :s :p :o )>> .
>
> means a SPARQL query can find the subject:
>
>     ?X rdf:reifies ?T .
>     bind (SUBJECT(?T) as ?subj)
>
>          Andy
>
>