Re: An outline of RDFn -- RDF with (auto- and custom-) names

Hi Andy,

On Thu, Nov 30, 2023 at 1:57 PM Andy Seaborne <andy@apache.org> wrote:
>
>
>
> On 27/11/2023 21:37, Thomas Lörtsch wrote:
> > I think it has been established that most use cases can be characterized
> >   as annotating tokens, not types (if that still isn’t common wisdom then
> >   that would be a very important discussion to have first).
>
> For proposals that do not also include types in the data model -
>
> Can there be two different tokens of the same type in a single graph? How?

Yes. How depends on what the token is.

If it's just old-school reification; two rdf:Statements with different
identifiers (bnodes or IRIs) who both have the same values for
rdf:subject, rdf:predicate and rdf:object (and exactly one of each).
The "type" here is thus quite informal (but understandable, I
believe).

If it's based on named graphs with semantics (like option 3.4 in RDF
datasets [1]), yes-and-no, since only the "name tokens" referring to
those are in a single graph, and the type is based on the equality of
the two other graphs that these tokens "name". And this equality
depends on more than their "inherent" triples I think, specifically
which entailments they're under and whether other graphs are "visible"
(determined via relationships from/to the graph name; akin to
owl:imports).

This is certainly not formally good enough without semantics for
datasets. (And I just posted an attempt which I hope is less
far-reaching and closer to what you are thinking of.)

> Conversely, can multiple triples refer to the same token
> with requiring specific syntax (c.f Turtle ";")

Yes, by using the same identifier (blank node or IRI).

> With type and a triple to relate token and type, both are possible and
> it is preserved on RDF merge.

Yes. I am interested in the graph terms idea you have in this regard.
Would two sets of triples with a graph term identifier in the fourth
position merge in a redundant way (e.g. resulting in the same triple
but with different graph term identifiers), or would there be a
structural graph identity check and some relabelling? (I guess no, and
that this would be left to a more expensive *union* operation,
possibly relying on RDF C14N?)

Best regards,
Niklas

[1]: <https://www.w3.org/TR/rdf11-datasets/#each-named-graph-defines-its-own-context>

>      Andy
>

Received on Thursday, 30 November 2023 14:53:53 UTC