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

On 16/02/2024 19:26, Peter F. Patel-Schneider wrote:
> (...)
>> In the following, I'll use a lisp-like representation of the 
>> *abstract* syntax, hopefully self-explanatory.
>
> Please don't - this just makes things much harder to read.
Since Enrico introduced a new abstract syntax (compared to the ones in 
the table),
and since he did not explicitly provide a mapping to the concrete syntax,
I chose to avoid presuming of such a mapping.

(...)

>
>> 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
>
> I think what you are trying to say is that if tripleOccurence is part 
> of RDF graphs then pattern matching has to be extended. Well, yes, 
> just like if tripleTerm is part of RDF graphs pattern matching has to 
> be extended as well. It is just that the extension for the latter is 
> simple.  To match tripleTerm, just match the components.  The 
> situation for tripleOccurence is a bit more complex - if there is 
> something like rdf:nameOf then there is a post-graph expansion and 
> then regular pattern matching; if there isn't then part of pattern 
> matching is to construct a side partial mapping from IRIs to triple 
> terms use that mapping to expand matching for IRIs.  But the point is 
> that no matter what additions are made to RDF graphs pattern matching 
> has to be expanded.

Note that I wrote "no SIMPLE pattern matching".

As you point out, extending the current "pattern matching" (more 
formally, the notion of graph instance in the semantics [1]) to triple 
term would be straightforward.

Granted, we could maybe extend this definition to cover the entailment 
suggested in my email. But I'm concerned that it would 1) depart from 
the intuitive notion of patter matching, 2) be computationally more 
expensive, and 3) have strange consequences on SPARQL (see my other 
email [2]).

[1] https://www.w3.org/TR/rdf11-semantics/#dfn-instance

[2] 
https://lists.w3.org/Archives/Public/public-rdf-star-wg/2024Feb/0030.html

>
> peter
>
>