W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > June 2002

Re: datatyping unstaked

From: patrick hayes <phayes@ai.uwf.edu>
Date: Fri, 14 Jun 2002 20:45:14 -0500
Message-Id: <p05111a19b9304bd19710@[65.217.30.123]>
To: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Cc: w3c-rdfcore-wg@w3.org

>On first pass, I find this an improvement on the current datatyping, 
>and is far better suited to the requirements of CC/PP.
>
>I need to study this more carefully, but meanwhile have a couple of 
>small comments:
>
>>Second, we could introduce a special property called something like 
>>rdfd:rigidliteral, which forces a literal to be interpreted 
>>literally, as it were. This acts like a datatype property, but what 
>>it says is that the literal really does denote itself: its a kind 
>>of pre-emptive datatype-exclusion device which produces a datatype 
>>clash with any datatype. The semantics is that it forces D to be 
>>the identity map in its object, and it denotes equality. Then we 
>>could get the current meaning by writing things like
>
>Wouldn't asserting a datatype of xsd:string (which maps literal 
>strings to themselves) on the corresponding property have the same 
>effect?

Yes, it would (provided we say that those strings in literals really 
are xsd:strings: Im not sure if some people might want to argue that 
each datatype defines it sown notion of 'string'.) I just thought we 
could use this without appealing to any external datatypes. Maybe 
this isnt such a great idea, in any case.

>Or, for example, using xsd:string datatype mapping, as in:
>
>   <ex:Jenny> <ex:age> _:x .
>   _:x <xsd:string> "10" .
>
>I can't see what value rdfd:rigidliteral would add.
>
>>One way to rule things like this out, if someone wanted to do that, would be:
>>
>><rdfs:range> <rdfs:subPropertyOf> < rdfd:rangedatatype>  .
>
>Isn't that potentially non-monotonic?  (I think this is a general 
>problem with making additional assertions about core RDF vocabulary.)

I don't quite see how. It would certainly be rather a dangerous thing 
to assert in general, which is why I was only half-serious, but I 
think it would be monotonic. I hope so, anyway. Can you give more 
details? You have me worried.

Pat


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Received on Friday, 14 June 2002 21:45:13 EDT

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