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RE: SEM: 5.1 literal/data values

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Fri, 19 Jul 2002 06:20:25 -0400
To: michael.smith@eds.com
Cc: www-webont-wg@w3.org
Message-Id: <20020719062025K.pfps@research.bell-labs.com>

From: "Smith, Michael K" <michael.smith@eds.com>
Subject: RE: SEM: 5.1 literal/data values
Date: Thu, 18 Jul 2002 19:03:52 -0500

[...]

> I do not expect OWL systems to be able to reason about integers, XML
> Schema dataype cardinality, the length of strings, and many other XML
> Schema Datatype properties.  

Why not?  If these things are in OWL, then an OWL system should be able to
reason about them.  For example, I would expect an OWL reasoner to be able
to determine that there are only 11 integers in the range from 0 and 10
inclusive, provided that such ranges are allowable in OWL.  To expect
otherwise is to say that integer ranges are not really part of OWL.

Now XML Schema datatypes have many mysterious and wonderful aspects, such
as datatypes defined by regular expressions.  It may be that the WG does
not include all of XML Schema in OWL, but the parts that do make it in
should *really* make it in.

> In fact, I am kind of surprised that it appears that OWL reasoners are
> going to need to be able to recognize equality of datatype values (?).
> E.g. recognize that _a: and _b: below are equal (using one version of
> the proposed RDF syntax for datatype literals)
> 
>       _:a  <xsdr:decimal> "10" .
>       _:b  <xsdr:integer> "10" .

Again, if the XML Schema datatype integer and the XML Schema datatype
decimal are both in OWL, then I see no reason for an OWL system not to
understand that decimal and integer have the compatible lexical-to-value
mappings.

> I had earlier assumed that at best we would treat datatype value equality
> according to some trivial surface syntax canonicalization. (Which I
> guess could be made to work for this example.)

Well if this is the best that we would do with XML Schema datatypes, then I
suggest *not* including XML Schema datatypes at all.  Instead lets go with
a much simpler datatypeing scheme, perhaps only integers and strings.

> - Mike

[...]

peter
Received on Friday, 19 July 2002 06:20:38 GMT

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