Re: summary un/asserted

Here is a proposal that I don't think will go anywhere, and I might not 
totally believe in, but does connect to the working group's activities.

THESIS:  embedded triples are not a good solution to the use cases of the 
working group

EVIDENCE:

The use cases of the working group do not use embedded triples directly but 
instead require a separate resource that is connected to a triple.   These 
separate resources are needed because the information about an embedded triple 
from one use of it has to be separated from the information from other uses. 
Otherwise there is a mix-and-match problem, as shown in representing 
provenance where source from one provenance cannot be combined with time or 
access from another.  This problem affects the "seminal example", all kinds of 
provenance, and nearly all uses of embedded triples in the enoding of n-ary 
predicates.  The need for this extra resource and new linking predicate add to 
the complexity of just about any use of embedded triples in RDF and require 
extra shorthands in Turtle to partly hide this complexity from users.

SOLUTION:

The solution is to do away with the uniqueness of embedded triples and base 
the extension of RDF proposed by the working group instead on non-unique 
occurrences of triples.   If we leave the proposed syntax alone, we get an 
extension of RDF where
   << :a :b :c >> :d :e , :f :g .
   << :a :b :c >> :h :i , :j :k .
does *not* entail
   << :a :b :c >> :d :e , :h :i .

There are problems with this version of occurrences of triples.   Without some 
way of referencing a particular occurrence of a triple it is not possible to 
represent the above graphs in N-triples and all information about the 
occurence has to use a shorthand syntax in Turtle, making what used to be a 
convenience a necessity.   The solution to this problem is to in effect give 
these resources an identifier, so that a particular occurrence of a triple is 
no longer "anonymous" and can be referred to.

The way to do this is to allow IRIs and blank nodes in RDF to also be a triple 
occurence, with syntax something like (this syntax probably not good at all 
but you should get the idea)
   <:x< :a :b :c >> :d :e .
   <_:x< :a :b :c >> :d :e .
in both N-triples and Turtle.  This is a varation of a recent syntax proposal 
but is not just syntax and instead is the extension to the RDF data model to 
support quoted triples.

A big problem (and one reason that I don't totally believe this proposal) is 
using the same IRI or blank node for multiple triple occurrences as in
   <:x< :a :b :c >> :d :e .
   <:x< :f :g :h >> :d :e .
has to be handled by either forbidding it or allowing a node to have multiple 
triple occurrences.

peter

Received on Tuesday, 9 July 2024 15:01:58 UTC