Re: Consolidating triple/edges -- named occurrence version

On 5 Jan 2024, at 14:46, Olaf Hartig <olaf.hartig@liu.se> wrote:

On Fri, 2024-01-05 at 10:58 +0000, Franconi Enrico wrote:
On 5 Jan 2024, at 11:42, Niklas Lindström <lindstream@gmail.com>
wrote:
Of course, it has implications for how to define these occurrences
(truth-makers, right [1]?), which we need to come to terms with
together.
For example, I think this makes sense:

   << :wed-1 | :liz :spouse :richard >> .
   << :wed-1 | :richard :spouse :liz >> .
   :wed-1 a :Marriage ;
       :starts 1964 ;
       :ends 1974 .

Would you agree?


Yes, it does.

Notice that this diverges quite a bit from the Property Graph
perspective. PG folks would understand the IRI :wed-1 to be an
identifier of an edge, and they would see two edges here (one from :liz
to :richard and another one from :richard to :liz). Then, they would
get confused because two different edges cannot have the same
identifier.

I agree. However, as I observed yesterday, the identity of PG edges should be encoded in RDF by the property names (emulating a singleton property), and not by reification.
Reification then helps to add properties to the uniquely identified edges.
This is of course possible with the current semantics.

Notice also that a semantics such as this would probably not be very
useful for provenance use cases. I would assume that, in such use
cases, it makes a difference whether the provenance annotation is about
the triple (:liz, :source, :richard) or about the triple (:richard,
:source, :liz).

I also agree here. Proper provenance use cases do need a more “syntactical” approach and therefore some form of opacity.
However, the WG decided to go full steam to a fully transparent (i.e., semantic) approach.
That’s why yesterday I proposed that we could study extensions of this current approach to include optionally some form of opacity (whatever this may mean…).

cheers
—e.