Re: From syntactic to interpreted triple

Hi Peter,

On onsdag 10 februari 2021 kl. 11:12:01 CET Peter F. Patel-Schneider wrote:
> On 2/10/21 10:54 AM, Olaf Hartig wrote:
> > [...]
> > No, not in general. By the currently proposed semantics of RDF* [1,2], it
> > is not generally the case that an embedded triple can be used as
> > shorthand for the corresponding four reification triples. Consequently,
> > something like this is also not possible in queries.
> 
> There are other proposed semantics.

I only see these two as a pull request.

> > [...]
> > Having said that, in this thread here I have demonstrated that, even if we
> > cannot draw such inferences for embedded triples in general, it is still
> > possible to do so in specific contexts (namely, if an embedded triple is
> > the subject or object of a particular type of nested triple).
> 
> I'm unclear as to what facility this refers to.

Consider the following nested triple as an example (written in Turtle*, prefix 
declarations omitted).

  <<:cars :are :bad>> ex:statedBy :Alice .

It is possible to explicitly define the property ex:statedBy to have a 
semantics that applies referential transparency when used in nested triples 
such as the one above. Then, if we know that the URIs :cars and :automobiles 
denote the same thing, we can infer the following nested triple from the one 
above.

  <<:automobiles :are :bad>> ex:statedBy :Alice .

Earlier in this thread I have discussed this in detail; see:
https://lists.w3.org/Archives/Public/public-rdf-star/2021Jan/0108.html

In particular, I have defined this semantics of ex:statedBy in terms of a 
SPARQL CONSTRUCT query, which I repeat here for your convenience:

  PREFIX owl: <http://www.w3.org/2002/07/owl#>
  PREFIX ex: <http://example.org/>
  CONSTRUCT {
    <<?s2 ?p ?o2>> ex:statedBy ?mo .
  }
  WHERE {
    <<?s1 ?p ?o1>> ex:statedBy ?mo .
    {
      ?s1 owl:sameAs ?s2 .
      BIND( ?o1 AS ?o2 )
    }
    UNION
    {
      ?o1 owl:sameAs ?o2 .
      BIND( ?s1 AS ?s2 )
    }
    UNION
    {
      ?s1 owl:sameAs ?s2 .
      ?o1 owl:sameAs ?o2 .
    }
  }

 
Note that for this query I have assumed that owl:sameAs is used to express the 
semantic equivalence of URIs such as :cars and :automobiles.

Best,
Olaf


> > Best,
> > Olaf
> > 
> > [1] https://github.com/w3c/rdf-star/pull/81
> > [2] https://github.com/w3c/rdf-star/pull/88
>
> peter

Received on Wednesday, 10 February 2021 16:57:12 UTC