Re: Well-formedness for option 3

On 28 Feb 2024, at 17:09, Andy Seaborne <andy@apache.org> wrote:

I don't understand why the well-formedness / macros are in the semantics.

My documents is indeed an attempt to formalise the whole approach (not just the semantics); by the way, in order to define the semantics I need to formalise the abstract syntax as well.
A “macro” has to have anyway a syntactic definition as well in the abstract syntax.
*My* definition of well-formedness (also captured by the “upfront restricted abstract syntax”) is equivalent to just using reification through the macro.

We have the occurrence and annotation syntax in Turtle.
We don't have occurrence and annotation syntax in N-Triples, only the direct triple forms.

I am working at the level of abstract syntax. Clearly, if you define a macro in Turtle, this will have a counterpart in the abstract syntax as well.

A graph written in Turtle only using occurrence and annotation syntax will be "reification well-formed" but the definition isn't tied to the macros. It is having triple terms only in the object position of rdf:nameOf and that can be applied to a N-triples.

I have shown that these two ways to look at "reification well-formedness” are equivalent, according to my definitions.
Note that, as I have shown in the “upfront restricted abstract syntax”, well-formedness is more than what you said above.

The macros do not allow a graph of just an occurrence because macros require that the occurrence be used somewhere. The "reification well-formed" condition does not. That is, a graph that is all "occurrences" (edges) does not fit the macros.

*My* definition of reification well-formedness corresponds (as I strongly believe) to the usage of occurrences in triples, so in my case what you are saying is not true. And if you check the  “upfront restricted abstract syntax” you can see that.

An idea to eliminate the aforementioned disadvantage of including
Property 2 is to allow only blank nodes in the subject of rdf:nameOf
triples, but that’s probably not very desirable either because it would
mean that “occurrences” cannot be named by an IRI. Still, I thought I
should mention this idea as a possible option to address the
undesirable effect on graph merging that Property 2 would imply.

I prefer to "advise" use of blank nodes when a URI isn't needed and indeed we have special syntax in Turtle for that << :s :p :o >>. Saying "must not" is too strong. I'm not sure making this stronger uniquely for RDF-star is in the style or RDF.

Well, in our most popular example, we do have a URI 🙂
https://fancdesigns.com/elizabeth-taylor-and-richard-burtons-first-wedding/

On a more serious note, many famous events do appear in wikidata, e.g.:
https://www.wikidata.org/wiki/Q10806


cheers
—e.