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Re: Datatyping Summary

From: Martyn Horner <martyn.horner@profium.com>
Date: Wed, 30 Jan 2002 11:50:05 +0100
Message-ID: <3C57CFDD.C57E4096@profium.com>
To: Patrick Stickler <patrick.stickler@nokia.com>
CC: Dan Connolly <connolly@w3.org>, Brian McBride <bwm@hplb.hpl.hp.com>, RDF Core <w3c-rdfcore-wg@w3.org>, Jeremy Carroll <jjc@hplb.hpl.hp.com>, Sergey Melnik <melnik@db.stanford.edu>
Patrick Stickler wrote:
> 
> On 2002-01-29 0:17, "ext Dan Connolly" <connolly@w3.org> wrote:
> 
> >> This is similar to B2.  I've changed the example slightly from Sergey's.
> >> Consider the graph:
> >>
> >>    _:f <rdf:type> <film> .
> >>    _:f <dc:Title> "10" .
> >>    <mary> <age> "10" .
> >>
> >> Given a query:
> >>
> >>    (?x <dc:Title> ?y) & (?z <age> ?y)
> >>
> >> existing applications will return:
> >>
> >>    ?x = _:f, ?y = "10", ?z = <mary>
> >>
> >> Under TDL, they would return null.
> 
> (apologies in advance for the lengthy reply, please
>  bear with me... I've made it as terse as I dare)
> 
> I believe that Jeremy's recent 1984 example (in
> addition to other examples provided over the past
> few days) clearly demonstrates that a literal
> does not have consistent global meaning. Whether
> the meaning of a literal is expressed in RDF or
> externally by application is beside the point.
> 
....snip...
> Now, given a query:
> 
>     (?x <dc:Title> ?y) & (?z <age> ?y)
> 
> every application should return null because the value
> denoted by ("10", xsd:string) is not the same value
> denoted by ("10", xsd:integer).
> 
> Thus in conclusion (and you thought I would never get
> there ;-) an application which equates the two occurrences
> of "10" as the same value and successfully returns a
> result for the specifiec query is in fact broken, as it
> misses the point that two different values are denoted.
> 
> Patrick

If this is the end of the thread, I can safely add my 0.02 euros:

This is what I've implemented for the sake of promoting (a) long-term
survival of distinct information and (b) good practices in dependent
applications. As much as possible and as far as we can economically
police it, comparisons of semantically different objects throws an
exception. It's not an empty set: it's broken - a bad question. `Give me
a film called the same as Mary's age' is a kid's puzzle and will not
lead to an enhancement in world knowledge.

-- 
Martyn Horner <martyn.horner@profium.com>
Profium, Les Espaces de Sophia,
Immeuble Delta, B.P. 037, F-06901 Sophia-Antipolis, France
Tel. +33 (0)4.93.95.31.44 Fax. +33 (0)4.93.95.52.58
Mob. +33 (0)6.21.01.54.56 Internet: http://www.profium.com
Received on Wednesday, 30 January 2002 05:50:55 EST

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