RE: Interpretation of RDF reification

Hi Lars,

There are those who regard reification with some trepidation; there are
no doubt gremlins lurking in its inner workings.  The RDFCore working
group decided not to attempt to define a formal semantics for it, though
it did do a little clarification which I will get to below. 


> If I create an RDF node that reifies the statement
>    (winston, married-to, clementine)
> what does that node represent? Specifically, does it represent the
> *statement* that these two are married,

Close but not exactly.

> or does it represent the
> *marriage* relationship between them?


> That is, if the 
> reifying RDF node is x, which of the following two statements 
> wouldn't make sense?
>    (x, start-date, 1908-09-02)
>    (x, according-to, wikipedia)

The clarification that RDFCore made was between statements and statings.
There is a test case somewhere - I don't have the reference to hand.

If x is, as you say a reification of (s, p, o) for some s, p, and o.

And y is also a reification of (s, p, o), then is x necessarily the same
thing as y, e.g. does (x, wasStatedIn, foo) entail (imply) (y,
wasStatedIn, foo)

The answer is no.  X represents the stating of the statement, or the
occurrence of the statement, not the statement itself.

> I suspect the answer is that RDF nodes reifying statements 
> really do represent the statements. If that's the case, what 
> is the usual way of meeting the other use case in RDF?

What do you intend to do with this "marriage relationship"?  To
understand your use case, I'd like to know what sort of statements you'd
like to make about the relatioship.


Received on Wednesday, 22 March 2006 20:58:04 UTC