Re: Update RDF-star semantics document

On 12 Mar 2024, at 23:09, Peter F. Patel-Schneider <pfpschneider@gmail.com> wrote:
This is ambiguous as the nor can be given a wide scope.

"An RDF graph which does not contain any triple term nor any rdf:reifies triple but for the ones coming from the expansion of the macro for triple reification is called reification well-formed."

Better would be

"An RDF graph where the only triple terms are objects of triples with predicate rdf:reifies."

This is unambiguous, but more liberal as it allows objects of rdf:reifies triples to be anything.  I don't think that the liberalization causes any problems.

Nope, you would allow, e.g., isolated “edge” triple.

If you want to define well-formedness by a syntactic restriction and not via the macro expansion, then my document gives the exact grammar at the end; there is no need of other definitions.

graph      ::= (triple | (identifier_i rdf:reifies tripleTerm
                          (subject predicate identifier_i) | (identifier_i predicate object)))*
triple     ::= subject predicate object
subject    ::= iri | BlankNode
predicate  ::= iri
object     ::= iri | BlankNode | literal
tripleTerm ::= triple
identifier ::= iri | BlankNode
iri        ::= any_iri_but_rdf:reifies

(Note: syntactic categories adorned with equal subscripts in the grammar above enforce a non-context-free equality condition on the respective tokens.)

I don’t see any purpose to have a well-formedness which is not capturing exactly the macro expansion, which is the only way we give meaning to reification.

—e.