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Re: The Cannes Entailment [was: Coming to grips with the entailment put forth by Jeremy]

From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Date: Mon, 29 Apr 2002 12:07:02 +0100
Message-Id: <5.1.0.14.2.20020429115430.03cbb010@joy.songbird.com>
To: Brian McBride <bwm@hplb.hpl.hp.com>
Cc: Patrick Stickler <patrick.stickler@nokia.com>, RDF Core <w3c-rdfcore-wg@w3.org>
At 05:18 PM 4/28/02 +0100, Brian McBride wrote:
>The know fix
>============
>
>In the know fix, we assume that the knowledge that
>
>   <jenny> <age> "10" .
>
>really means
>
>   <jenny> <age> _:a .
>   _:a <xsd:decimal> "10" .
>
>is defined elsewhere.  Perhaps an application just 'knows' that this is 
>the case.  Perhaps there are some rules defined outside of RDF for 
>expressing this.  However, its done, we take the view that if you want to 
>do this sort of thing, you do it extra-rdf.

Roughly, I think that this is what we currently have.  RDF know's nothing 
about the nature of "10", but further knowledge may come from out-of-band 
information.

EXCEPT: the "really means" implies that the original statement interpreted 
according to the current model theory may be not true (i.e. <I(jenny), 
I("10")> is not in the relational extension of I(age)), which I think would 
be broken in the face of the tidy literals decision.  SO, I think there are 
two sub-choices for this fix:

(a) "knows" with tidy literals (i.e. I("10")=="10")
(b) "knows" without tidy literals


>The Rule Fix
>============
>
>We build a rule mechanism, as in the know fix, into RDF.

I think adding rules to RDF is a substantial change and out of 
scope.  Especially this late in the WG cycle.

>The Syntax Fix
>==============
>
>This fix is based on the idea that viewing the problem as an entailment 
>problem is incorrect.  The real problem is syntactic.  It arises solely 
>from the fact that folks are currently used to writing in rdf/xml:
>
>   <rdf:Descrption rdf:about="#jenny">
>     <age>10</age>
>   </rdf:Description>
>
>and it is suggested that they expect the age property to represent the 
>number not the numeral.
>
>The suggestion therefore, is to fix this in the syntax.  If instead the 
>author writes:
>
>   <rdf:Description rdf:about="#jenny">
>     <age xsi:type="xsd:decimal">10</age>
>   </rdf:Description>
>
>this should be equivalent to the following n-triples:
>
>   <jenny> <age> _:a .
>   _:a <xsd:decimal> "10" .
>
>Could the xsi:type property be inserted by an XML Schema or a DTD?

Again, this is a substantial change.

Also, it doesn't help CC/PP.

>The Abandon Hope Fix
>====================
...
>I strongly suggest we do not abandon hope until after we have sought 
>community feedback on the current proposal.

I agree.

#g


-------------------
Graham Klyne
<GK@NineByNine.org>
Received on Monday, 29 April 2002 07:03:58 EDT

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