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Re: datatypes: new information - email delayed awaiting WG response

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Thu, 04 Jul 2002 11:22:58 +0100
Message-Id: <5.1.0.14.0.20020704111324.020cb838@15.144.25.13>
To: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Cc: RDF Core <w3c-rdfcore-wg@w3.org>

At 20:44 03/07/2002 +0100, Graham Klyne wrote:
>At 04:58 PM 7/3/02 +0100, Brian McBride wrote:

[...]

>But I do think this is a matter of taste, rather than a forced outcome.

Yup, but its beginning to give me the heebee jeebees.


>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.

Right.  The logic survives, as best I can understand it, but is this the 
behaviour we want to specify?  Would someone ever want to build a language 
on top of RDFS which had some notion of a TOP property.  If they did, what 
would the implications for datatypes be?

Are we willing to accept the constraint that all subProperties of a 
property must have the same datatype constraint?  Or is there some magic in 
the model theory that can allow them not to?

I need to find time to sit and think about this.

Brian
Received on Thursday, 4 July 2002 06:23:40 EDT

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