Re: Nested Graphs - a graph-based proposal

This does not appear to be a proposal for nested graphs, but instead a 
proposal for identifying a subset of the triples in an RDF graph and allowing 
this set to be the subject or object of a triple.  So it appears to be an 
alternative syntax for one view of RDF datasets (as evidenced by the 
quad-based surface syntax) - the view where all the triples in the dataset are 
asserted.

However, there appears to be a decided change in semantics under the hood that 
is exposed in the querying section.  BGPs now appear to match against a bag of 
triples instead of matching against an RDF graph as the first query returns 
two results.  (It appears that the third query is incorrect and should have 
instead GRAPH ?g {  :Alice ?p ?o }.)

The idea that it is possible to have different "versions" of IRIs (e.g., 
potentially different ages for :Alice) in the same graph is also a change to 
RDF.  This change may make RDF better, but it is fundamental change.

I'm unclear as to what "standard RDF n-ary relations" refers to.

It is not the case that this proposal has the feature that "no intermediate 
node is required to differentiate different occurrences".  Instead this 
proposal has a built-in intermediate node, namely the graph name.  So the 
graph in a named graph is a type, and the name intermediates between the graph 
and uses of the graph as an occurrence.  This is very similar to the situation 
for predicates in RDF.

The semantics section of the proposal does not actually provide a semantics 
for nested graphs.   All that is says, implicitly, is that nested graphs are 
resources.  Then there is some discussion about quoting.   But this does not 
result in a semantics for nested graphs.


peter

Received on Thursday, 19 October 2023 18:21:47 UTC