Re: Consolidating triple/edges -- occurrence set version

Hi Andy,

Thanks for writing down this consolidation attempt! Unfortunately,
there seems to be a problem in there ...

On Wed, 2024-01-10 at 22:46 +0000, Andy Seaborne wrote:
> [...]
> 
> In this variation, the RDF abstract data model has "occurrences sets"
> as RDF terms.

Given that you say "as RDF terms", I assume that each such "occurrences
set" may be used as subject or object of an RDF triple. Correct?

Notice that this question is just asking for clarification, and it is
not actually relevant regarding the problem that I want to point out.

> An "occurrence set" for S,P,O is the set of all named occurrences
> that have S,P,O in those positions. There is one occurrence set for
> every triple.

I would have a question about the latter sentence but, since this is
also not relevant regarding the problem, I keep it for the moment.

The relevant part is in the first sentence of this paragraph; namely,
by the definition that you give here, the kind of things that an
"occurrence[s] set" contains are "named occurrences", for which next
you define:

> A named occurrences is a pair of (name, occurrence) where
> "occurrence" is member of an occurrence set.

Here comes the crux of the problem. By this definition, a "named
occurrence" contains something called "occurrence" that "is member of
an occurrence set". If I combine this definition with your definition
of "occurrence set" as given above, I notice that such an "occurrence"
(within a "named occurrence") must be a "named occurrence" because,
according to your definition of "occurrence set", the elements/members
of occurrence sets are "named occurrences". In other words, by these
definitions, every "named occurrence" contains a "named occurrence",
which contains a "named occurrence", etc. Hence, there is an
unresolvable cycle in these definitions.

Or did I misunderstand anything?

-Olaf


> Occurrence sets replace triple terms.
> https://lists.w3.org/Archives/Public/public-rdf-star-wg/2023Dec/0033.html

> 
> Named occurrences are not part of the RDF data model (abstract
> syntax).
> 
> The syntax <<[ ]>> is used below for now to be different to triple
> term 
> <<( )>>. Had that not been used already, it would be better as <<(
> )>> 
> because () is often used for tuples.
> 
> An implementation that wishes have great named occurrence
> performance 
> can have data structure for (n,s,p,o) with indexed lookup operations.
> 
> ## Turtle and N-Triples.
> 
>      << _:n | s p o >> :q :z .
> 
> is a syntax form and is equivalent to the N-triples:
> 
>      _:n rdf:occurrenceOf <<[ :s :p :o ]>> .
>      _:n :q :z .
> 
> "memberOf" or variants on "member" don't look good because
> rdfs:member 
> already exists.
> 
> Now given a name "n" (blank node or URI) found by some means, then
> 
>      _:n rdf:occurrenceOf ?X .
> 
> finds the occurrence set term, which has the subject/predicate and
> object.
> 
> Annotation syntax applies as before.
> 
> An RDF graph is a set of triples.
> There is no need for a virtual property.
> 
> It may work to have a class of occurrences for S/P/O where the 
> occurrence set is the class extension.
> 
>      Andy
> 
>

Received on Thursday, 11 January 2024 08:19:19 UTC