Re: RDF-star semantics: option 3 (first DRAFT)

On 16/02/2024 18:37, Franconi Enrico wrote:
> I am advocating (in my last email) just the opposite approach:
>
> - *disallow* triple terms, e.g.:
>
>     (triple-term (iri "ex:s") (iri "ex:p") (iri "ex:o))
>
> - and *disallow* rdf:nameOf triples, e.g.:
>
>     (triple

>        (iri "ex:e")

>        (iri "rdf:nameOf")

>        (triple-term (iri "ex:s") (iri "ex:p") (iri "ex:o))
  )
>
> - *keep only* triple occurrences terms, e.g.:
>     (triple
>        (triple-occurence (iri "ex:e") (iri "ex:s") (iri "ex:p") (iri 
> "ex:o))
>        (iri "ex:a”)
>        (iri "ex:b”)
>       )
>
> Just like in CG, there is simple encoding (in the shape of option 2) 
> in which simple entailment based on matching works.

Even if we disallow triple terms and keep only term occurrences, the 
entailment between the first 2 graphs in my email holds, despite the 
fact there is no subgraph of one that is an instance of the other -- 
i.e. no pattern matching between them.

Besides simple entailment, this means that SPARQL results will be tricky 
to define. What should

     SELECT ?x { ?x :a :b }

return for this graph ?
x = (triple-occurrence (iri "ex:e") (iri "ex:s") (iri "ex:p") (iri 
"ex:o")) -- as suggested by the 1st graph?
Or x = (iri "ex:e"), as suggested by the 2nd graph?
Or both??

> —e.
>
>
>> On 16 Feb 2024, at 18:17, Pierre-Antoine Champin 
>> <pierre-antoine@w3.org> wrote:
>>
>> Thanks Enrico for this proposal.
>>
>> I strongly suggest that we get rid of the orange part, with an 
>> argument similiar to what Andy brought up during the Semantics TF 
>> call today -- and pushing Andy's argument forward.
>>
>> The orange part make "triple occurrences"  part of the abstract 
>> syntax. Regardless of the name, I think it is a bad idea.
>>
>> In the following, I'll use a lisp-like representation of the 
>> *abstract* syntax, hopefully self-explanatory.
>>
>> (graph
>>   (triple
>>     (triple-occurence (iri "ex:e") (iri "ex:s") (iri "ex:p") (iri "ex:o))
>>     (iri "ex:a")
>>     (iri "ex:b")
>>   )
>>   (triple
>>     (iri "ex:e")
>>     (iri "ex:c")
>>     (iri "ex:d")
>>   )
>> )
>>
>> According to your semantics, it would be semantically equivalent to 
>> the following graph
>>
>> (graph
>>   (triple
>>     (iri "ex:e")
>>     (iri "ex:a")
>>     (iri "ex:b")
>>   )
>>   (triple
>>     (triple-occurence (iri "ex:e") (iri "ex:s") (iri "ex:p") (iri "ex:o))
>>     (iri "ex:c")
>>     (iri "ex:d")
>>   )
>> )
>>
>> which would also be equivalent to
>>
>> (graph
>>   (triple
>>     (iri "ex:e")
>>     (iri "ex:a")
>>     (iri "ex:b")
>>   )
>>   (triple
>>     (iri "ex:e")
>>     (iri "ex:c")
>>     (iri "ex:d")
>>   )
>>   (triple
>>     (iri "ex:e")
>>     (iri "rdf:nameOf")
>>     (triple-term (iri "ex:e") (iri "ex:s") (iri "ex:p") (iri "ex:o))
>>   )
>> )
>>
>> We are talking about *simple entailment* here, not some sophisticated 
>> semantic extension.
>> This breaks a very important feature of the simple entailment in RDF 
>> 1.1, namely: it can be computed by doing simple pattern matching of 
>> graphs: https://www.w3.org/TR/rdf11-semantics/#dfn-interpolation

>>
>> Clearly, there is no simple pattern matching method that can detect 
>> that the 3 graphs above entail each other.
>>
>>   pa
>>
>>
>> On 16/02/2024 15:58, Franconi Enrico wrote:
>>> RDF‐star semantics: option 3 
>>> <https://github.com/w3c/rdf-star-wg/wiki/RDF%E2%80%90star-semantics:-option-3>
>>> github.com 
>>> <https://github.com/w3c/rdf-star-wg/wiki/RDF%E2%80%90star-semantics:-option-3>
>>>  <apple-touch-icon-180x180-a80b8e11abe2.png> 
>>> <https://github.com/w3c/rdf-star-wg/wiki/RDF%E2%80%90star-semantics:-option-3> 
>>>
>>>
>>> <https://github.com/w3c/rdf-star-wg/wiki/RDF%E2%80%90star-semantics:-option-3>
>>>
>> <OpenPGP_0x9D1EDAEEEF98D438.asc>
>