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Re: Semantics of non-datatyped literals: Rationale (version 1)

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Tue, 01 Oct 2002 11:14:23 +0100
Message-Id: <5.1.0.14.0.20021001093902.02213d38@0-mail-1.hpl.hp.com>
To: Frank Manola <fmanola@mitre.org>
Cc: RDF Core <w3c-rdfcore-wg@w3.org>

At 08:55 30/09/2002 -0400, Frank Manola wrote:
>Brian--
>
>I don't mean to overly-complicate things,

Me too :)

>  but it's not clear to me that your expression of the issues captures all 
> the variants involved (maybe you're trying to do one thing at a 
> time?).  I may be wrong,

No your not.  I think your test cases help clarify what we mean by the 
tidy/untidy options.  Thanks for this.

>  but it seems to be that we also need to ask something like the following 
> questions as well (or at least to have these kinds of questions in mind 
> when deciding on our answers):

Just so.


>a.  what is the answer given the following RDF/XML
>
>   <rdf:Description rdf:about="Jenny">
>     <foo:age>10</foo:age>
>   </rdf:Description>
>   <rdf:Description rdf:about="John">
>     <foo:age rdf:datatype="&xsd;integer">10</foo:age>
>   </rdf:Description>
>
>[in particular, does this result in "Jenny and John have the same age", 
>"Jenny and John have different ages", or "I can't tell"]

With untidy the answer is "I can't tell".  With tidy I think the answer is 
no.  It can't be yes because we might have:

<rdf:Description rdf:about="Jenny">
     <foo:age>10</foo:age>
   </rdf:Description>
   <rdf:Description rdf:about="John">
     <foo:age rdf:datatype="&xsd;integer">10</foo:age>
   </rdf:Description>
   <rdf:Description rdf:about="film">
     <foo:title rdf:datatype="&xsd:string">10</foo:title>
   </rdf:Description>

John's age is clearly different to the title of the film, so Jenny's age 
can't be equal to both and there is no reason to prefer it being equal to 
John's age over the title of the film.

And the point about tidy is to answer these questins definitively, so 
"can't tell" ain't an option.




>b.  is the answer the same given the following RDF/XML
>
>   <rdf:Description rdf:about="Jenny">
>     <foo:age>10</foo:age>
>   </rdf:Description>
>   <rdf:Description rdf:about="Film">
>     <foo:title>10</foo:title>
>   </rdf:Description>
>
>together with a schema declaration
>
><rdf:Description rdf:about="#age">
>    <rdfs:range rdf:resource="&xsd;integer"/>
></rdf:Description>

This is an interesting one.  With untidy, then its a can't tell 
again.  With tidy, its a contradiction.  The argument above said that 
Jenny's age wasn't equal to xsd:integer"10".  In fact its not equal to any 
xsd:integer, therefore the value given is inconsistent with the range 
constraint.

Does this hold water?  Do others disagree?

Brian
Received on Tuesday, 1 October 2002 06:17:10 EDT

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