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Re: Datatyping Summary

From: <jos.deroo.jd@belgium.agfa.com>
Date: Wed, 30 Jan 2002 12:24:33 +0100
To: jjc@hplb.hpl.hp.com
Cc: w3c-rdfcore-wg@w3.org
Message-Id: <OF00FC2F89.BCEB6289-ONC1256B51.003C4A2C@bayer-ag.com>
[...]

> This framework allows me to illustrate an aspect of my "can't live" issue
> with S-B.
>
> S-B allows range constraints, in this example perhaps:
>
> <dc:title> <rdfs:range> <xsd:string.lex> .
> <age> <rdfs:range> <xsd:integer.lex> .
>
> I currently understand S-B as, within the RDF datatyping layer, insisting
> that "10" is a string.
> The two range constraints are used to:
> - constrain the set of possible strings
> - act as a hint to the application layer that:
>    * type conversion is possible
>    * type conversion is desirable.
>
> Thus given the database and the schema the application processing will
> correctly treat the title as a string, and the age as an integer. Good.
>
> Now, the query also operates in the application layer.
> This returns true.
>
> Thus in the application layer we have the following facts being the case:
>   The film has the title "10".
>   mary has age 10.
>   The age of mary is the title of the film.
>    i.e. that 10 is "10"
>
> There is a type clash here, and the combination is a logical error.

I don't follow Jeremy
i.e I don't see how you can draw the S-B conclusion
  The age of mary is the title of the film.
(where I suppose you mean age-value and title-value)

given

  :Mary :age "10" .
  :film :title "10" .

  :age rdfs:range xsd:int.lex .
  :title rdfs:range xsd:string.lex .

the query

  :Mary :age _:x .
  :film :title _:x .

will succeed
and I don't see any problem with that

nothing can be deduced w.r.t. values
i.e.
  dt1(v1) = dt2(v2)
does *not* mean that v1 = v2

--
Jos
Received on Wednesday, 30 January 2002 06:26:08 EST

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