Re: [RDF 1.2 N-Triples] Clarification on tripleTerm production

Hi Nik,

On 03/08/2024 11:01, Dominik George wrote:
> Hi RDF-star WG,
> 
> I have two questions about the current draft of RDF 1.2 N-Triple [1].
> 
> 
> As I read it, the draft has two conflicting definitions for how to write
> a triple term. Section 2.2 on Triple Terms states:
> 
>> A triple term is represented as a tripleTerm with subject, predicate, and
>> object preceded by <<, and followed by >>. Note that triple terms may be nested.
> 
> The grammar in 5.3, however, produces the triple term as follow:
> 
>> tripleTerm  ::=  '<<(' subject predicate object ')>>'
> 
> As we can see, the delimiters are '<<(' and ')>>', including parenthesis
> in addition to the less-than and greater-than pairs.

Yes - the terminals are '<<(' and ')>>', 3 characters each.

> Furthermore, the draft contradicts itself in where triple terms may
> occur.
> 
> While the Abstract states…
> 
>> RDF 1.2 N-Triples introduces triple terms as a fourth kind of RDF term which can
>> be used as the subject or object of another triple
> 
> … throughout the rest of the document, it is assumed that triple terms
> may only be the object of a triple.

The WG hasn't completely settled on this yet.

> If I were asked, I'd clarify as follows:
> 
> The production rules in the grammar on triple terms should be changed
> to only require '<<' and '>>' as delimiters. The additional
> parenthesis are not necessary for disambiguation, as the only production
> that could collide (IRIREF) does not allow a second less-than character
> after its opening delimiter.

Yes, in N-triples << and >> are not used.

These tokens are used in Turtle for reifiedTriples, not tripleTerms.

Because N-triples is a subset of Turtle, the tokens have to have the 
same meaning.  So in N-triples, a triple term has to be shown by '<<(' 
')>>' as it is in Turtle.

This area is a change from the RDF-star CG.

> As RDF 1.2 Concepts only allow for triple terms in the object position,
> the abstract should be corrected to remove the suggestion that triple
> terms can be used in the subject position.
> 
> 
> Thanks for considering,
> Nik
> 
> [1] https://www.w3.org/TR/rdf12-n-triples/

Received on Wednesday, 7 August 2024 10:02:44 UTC