Re: Two profiles: technical definition

On Thu, 2024-05-02 at 14:54 +0000, Franconi Enrico wrote:
> On 2 May 2024, at 16:24, Olaf Hartig <olaf.hartig@liu.se> wrote:
> > I have one more observation regarding the "functional opaque"
> > profile. Can you please confirm whether this observation is
> > correct.
> > 
> > By the given definitions, there is no syntactic restriction that
> > enforces the many-to-one cardinality constraint for rdf:edge
> > relationships. I mean, it would still be possible to have an RDF
> > graph that contains both of the following two triples:
> > 
> > ( :r, rdf:edge, (:s1, :p1, :o1) )
> > ( :r, rdf:edge, (:s2, :p2, :o2) )
> > 
> > What the given definitions of the "functional opaque" profile
> > provide is that there exists no interpretation that is a model of
> > such an RDF graph. Correct?
> 
> Yes.

Thanks for the confirmation.

> We could also enforce a syntactic restriction directly, so to avoid
> the introduction of inconsistent graph in simple RDF.

I think that adding such a syntactic restriction as a constraint (for
the "functional opaque" profile!) would make sense. This way,
implementations that focus on this profile may check this constraint
directly in the context of load and update operations, and reject any
load or update that would violate this constraint, which makes it
possible for such implementations to employ a physical schema that
relies on the fact that the relation denoted by rdf:edge is many-to-
one.

-Olaf


> —e.
> 
> > On Thu, 2024-05-02 at 07:05 +0000, Franconi Enrico wrote:
> > > 
> > > (I repeat a previous email, which could have been lost within a
> > > previous thread)
> > > 
> > > In order to make the upcoming discussion more concrete and
> > > technical,
> > > I have written down the formal definition of two profiles in the
> > > wiki:
> > > RDF-star profile “transparent” (namely many-to-many transparent)
> > > RDF-star profile "functional opaque” (namely many-to-one opaque)
> > > They rely on two distinct properties - rdf:reifies and rdf:edge
> > > (temporary name) - and on two distinct syntactic categories -
> > > tripleTerm and opaqueTripleTerm.
> > > Technically, they could be just merged into a unique profile,
> > > which
> > > actually could be RDF-star itself.
> > > 
> > > —e.

Received on Thursday, 2 May 2024 15:59:41 UTC