- From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
- Date: Wed, 03 Jul 2002 20:44:31 +0100
- To: Brian McBride <bwm@hplb.hpl.hp.com>
- Cc: RDF Core <w3c-rdfcore-wg@w3.org>
At 04:58 PM 7/3/02 +0100, Brian McBride wrote:
>I was about to send out the datatypes message to rdf interest, but I'm
>concerned that we have new information that means I need to change it.
>
>Have we agreed that test A does not hold for untidy literals? Patrick
>has, and I think Jeremy has. If so then I need to modify (simplify) the
>message - tests B and C can be dropped.
>
>The reasons we might decide that test A does not hold are:
>
> o it requires a special case in the reification machinery
> o it requires a special case in the container machinery
> o it interacts badly with rdfs:subPropertyOf
>
>http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Jul/0004.html
>http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Jul/0009.html
Hmmm... I could live with one special case (for reification), but I'm less
comfortable with two (for containers as well). I think it would be
perfectly possible to have special semantics for these cases, but it starts
to feel less reasonable. Which, to me, makes the entailment:
a someProp "lit" .
b someProp "lit" .
|=
a someProp _:x .
b someProp _:x .
look less feasible in the absence of:
a someProp "lit" .
b anotherProp "lit" .
|=
a someProp _:x .
b anotherProp _:x .
But I do think this is a matter of taste, rather than a forced outcome.
As for:
>http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Jul/0011.html
I'm inclined to say "relax", but I'd be too tentative to be convincing.
If we have:
a someProp "lit" .
b someProp "lit" .
|=
a someProp _:x .
b someProp _:x .
I think it's pretty clear that:
_:a dc:title "4th July" .
_:b dc:date "4th July" .
dc:title rdfs:subPropertyOf dc:property .
dc:date rdfs:subPropertyOf dc:property .
|=
_:a dc:property _:l .
_:b dc:property _:l .
So the problem you raise is what happens when different datatypes are
applied to dc:title and dc:date? If the datatypes have no literal->value
mappings in common, then I think that simply means the graph is not
satisfiable. I.e. there is no (DT-)interpretation that satisfies the
antecedent so the entailment is trivially valid.
(Datatyping, as currently discussed, applies only to a specific property
and not necessarily to its superproperties.)
#g
-------------------
Graham Klyne
<GK@NineByNine.org>
Received on Wednesday, 3 July 2002 18:07:56 UTC