Re: Against the notion of reification well-formed graph (i.e., atomicity)

> On 23. Jan 2024, at 12:50, Peter F. Patel-Schneider <pfpschneider@gmail.com> wrote:
> 
> On 1/23/24 06:30, Thomas Lörtsch wrote:
>>> On 23. Jan 2024, at 12:22, Peter F. Patel-Schneider <pfpschneider@gmail.com> wrote:
>>> 
> [..]
>>> 
>>> What the proposal does talk about is RDF reifications, nodes in an RDF graph that are subjects of rdf:subject, rdf:predicate, or rdf:object triples.  The well-formedness requirement states that an RDF graph is ill-formed if it has a node that is the subject of a triple with any of these predicates and is not the subject of exactly
>> Shouldn’t this be changed to *at least*? See my prior mail in response to Dörthe.
>>> one triple with each of these predicates.  No bijection between triples and anything is either mentioned or implied.  The notion of well-formedness is completely syntactic.
> 
> [...]
> 
> The proposal is *exactly*.  Changing to *at least* could make it harder to optimize RDF reifications in implementations.
> 
> As far as I can tell, multiple subjects, predicates, or objects is more difficult to optimize than missing subjects, predicates, or objects, but I haven't implemented an RDF triple store that optimizes RDF reifications.

But what does it *mean*? Optimizations should only be applied after we know that it means what we want it to mean.

I just realized that saying *at least* makes an implicit assumption about different terms in object position refering to the same entity in the realm of interpretation, i.e. a kind of owl:sameAs-ness. That may be way beyond what we want fix, and insofar saying *exactly* might be the safer and more restrained definition.
Still it introduces a hint of opacity that I’m not happy with.

Thomas

> peter
>

Received on Tuesday, 23 January 2024 12:09:06 UTC