Re: assertions on facts

good afternoon;

> On 22. Aug 2025, at 17:35, Peter F. Patel-Schneider <pfpschneider@gmail.com> wrote:
> 
> In the meeting yesterday there was discussion on whether RDF 1.2 currently supports assertions on facts (asserted triples).  My claim is that it does, and in a way that needs no change to Semantics.
> 
> During the meeting there was some discussion about some text that I authored. I believe that the text is
> https://github.com/w3c/rdf-concepts/pull/220#issuecomment-3113421890
> 
> That text, in essence, says that Semantics provides the basic machinery to talk about assertions on facts because it defines facts in an interpretation. This is then used to define facts asserted by a graph.  That's all the semantic machinery that is needed to support assertions on facts.
> 
> 
> The remaining part is to call on the intended meaning of rdf:reifies and say (not in Semantics) that an assertion about a fact in a graph is a triple whose subject is a reifier of a triple where the object of the reification triple is (denotes) a fact in the graph.  So ex:r ex:source ex:NYT is an assertion about the fact ex:John ex:loves ex:Mary in
> 
> ex:r rdf:reifies <<( ex:John ex:loves ex:Mary )>> .
> ex:John ex:loves ex:Mary .
> 
> This remaining part is not suitable for Semantics, in my opinion, as it does not provide any semantic machinery but is instead about the intended meaning of rdf:reifies and how rdf:reifies is supposed to be used.  As far as Semantics is concerned, any property could be used.  This is a decided positive, as it allows any property to be used in a similar way, perhaps with a stronger intended meaning or perhaps with a weaker intended meaning.


in the rdf 1.2 semantics document, rdf:reifies appears in four different term lists.
nothing appears about its meaning.

in the rdf 1.2 concepts document, it appears three times.
two appearances are in diagrams.
the third appearance is limited to a text passage which describes just that the term appears as the predicate in a reifying triple, but does not describe what that means.

the rdf 1.2 primer includes the term once as the special predicate of a reifying triple.

nothing in any of those documents describes what the a reifying triple means.
that is, nothing defines how these two new features - propositions and rdf:reifies, are to be used to provide the capability set out in the charter: to provide the feature formulated by the rdf-star community group, to make statements about asserted statements.
there has been correspondence to suggest that the rdf:reifies term is not even significant and that any predicate could serve an analogous role.
without a specific meaning, there is no reason to include the term in the either the concepts or the semantics document.

based on the current content of these documents i would not concur with a decision to advance them to candidate recommendation status.

as alternatives, the working group could work towards some combination of
- introduce a proper formal semantics for reifying triples as per pfps’ sketch.
- include a note in the semantics document to explain why the group refrains from that doing that.
- remove the rdf:reifies term and related text from all documents other than the primer and formulate illustrative text in that document only.
- approve the related prs to make the limits of the formalization clear and add a notes to explain the concerns.
- include rdf:reifies, but without privilege rdf:asserts, along with, for example. rdf:mentions (i.e. weaker and stronger meanings, as pfps suggested) 

my concern is that these documents should serve to promote a shared understanding of how to work with the features which they introduce.
throughout rdf history, that shared understanding has depended on formal definitions for the interpretations.
while it may be true that the current documents provide a basis upon which one could formulate one, they provide none.
they should not be promoted to candidate status as if they do.

---
james anderson | james@dydra.com | https://dydra.com

Received on Thursday, 28 August 2025 13:22:12 UTC