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RE: RDF Datatyping Working Draft

From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Date: Thu, 04 Apr 2002 14:06:55 +0100
Message-Id: <5.1.0.14.2.20020404135040.03cdac80@joy.songbird.com>
To: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
Cc: "Patrick Stickler" <patrick.stickler@nokia.com>, "Pat Hayes" <phayes@ai.uwf.edu>, "RDF Core" <w3c-rdfcore-wg@w3.org>
All,

I don't have as much time for reading drafts these days, so I'm waiting for 
the datatyping draft to be declared reasonably stable before I tackle 
it.  Thus my comments below are in response to Jeremy's comments rather 
that to Patrick's work-in-progress draft.

At 12:36 PM 4/4/02 +0100, Jeremy Carroll wrote:

>Patrick,
>
>if I have understood your comments about datatype interpretation correctly
>then I believe that:
>
>----
>
><ex:age> <rdfd:range> <xsd:integer> .
><Jane> <ex:age> "25" .
>
>datatype entails
>
><Jane> <ex:age> _:b .
>_:b <xsd:integer> "25" .

Based on my reading of Pat's "tidy literals" draft, I certainly didn't 
expect that entailment.

Offhand, I'm not seeing that this entailment in any way non-monotonic.

>---
>
>something that Pat seemed to shy away from saying in section 5.
>
>This continues to worry me because then in something like webont or DAML we
>can't say that ex:age has a unique value, because <Jane> has two really
>different ages: 25 the integer (i.e. the same age as <John> and <Judy>) and
>"25" the string (i.e the same as the <bar> of <foo>).

Ah, I see your worry.  It doesn't look like a pretty basis for building the 
higher layers.

>The positive suggestions I intend to list as alternatives for escaping the
>problems I see are:
>- don't do datatyping
>- drop tidy literals and don't have any model theory for datatyping
>- drop tidy literals and don't support the datateype property idiom (aka
>S-A)
>- don't support the inline idiom (aka S-B)
>- drop tidy literals and buy Pat's sophistry
>[[[
>These two forms - the single triple with a literal as object, and the
>similar triple with a bnode as object, together with a lexical form triple
>linking the bnode to the literal - are identical in meaning and can be
>substituted freely for one another.
>]]]
>
>http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Feb/0614.html
>
>I strongly prefer the last of these, and remain convinced that the costs of
>the current proposal in terms of loss of monotonicity or loss of mono-valued
>functions is unacceptable.
>
>Please remember the process no longer requires my points to be addressed
>(unless at the director's insistence). It is, IMO, more important to produce
>a document for the community to see than to address my concerns.

For the group's information, and also not expecting any reconsideration at 
this time, I agree with Jeremy on the technical points.  The earlier 
proposal at http://www.coginst.uwf.edu/users/phayes/simpledatatype2.html, 
not having tidy literals, looks better to me.

#g


-------------------
Graham Klyne
<GK@NineByNine.org>
Received on Thursday, 4 April 2002 08:11:22 EST

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