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Re: From syntactic to interpreted triple

From: James Anderson <anderson.james.1955@gmail.com>
Date: Wed, 10 Feb 2021 19:21:25 +0100
Message-Id: <FC7CB9E4-36AE-41AA-9EE2-A636D83AB12C@gmail.com>
To: public-rdf-star@w3.org

> On 2021-02-10, at 18:32:39, Peter F. Patel-Schneider <pfpschneider@gmail.com> wrote:
> 
> 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.

the example continues a thread which was in response to my request for the operations which one could perform on a sparql/graph-store endpoint to produce results which correspond to the “semantics".

i understood them to be intended to be illustrative only.

> 
> 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 18:21:43 UTC

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