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Re: From syntactic to interpreted triple

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Wed, 10 Feb 2021 12:32:39 -0500
To: public-rdf-star@w3.org
Message-ID: <bbe86f83-4bd6-6ef1-fa6e-037163a36c91@gmail.com>
As far as I know, "proposed semantics" includes more than just PRs.   But 
there is even a PR with a different semantics - 88.  But there are as well 
several semantics that have been proposed in the mailing list.

You appear to be postulating that RDF* semantics includes SPARQL* construct 
queries.  As far as I am concerned that's out of RDF* bounds.

peter




On 2/10/21 11:56 AM, Olaf Hartig wrote:
> 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 17:32:53 UTC

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