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Re: Dataypes, literals, syntax

From: pat hayes <phayes@ai.uwf.edu>
Date: Fri, 19 Jul 2002 16:22:06 -0500
Message-Id: <p05111b0bb95e30c323f2@[65.217.30.45]>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, Jonathan Borden <jonathan@openhealth.org>
Cc: www-rdf-logic@w3.org

>From: "Jonathan Borden" <jonathan@openhealth.org>
>Subject: Dataypes, literals, syntax
>Date: Fri, 19 Jul 2002 08:56:02 -0400
>
>>
>>  I just noticed:
>>  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Jul/0121.html
>>
>>  It got me thinking about literal datatypes (the above considers XML
>>  datatypes).
>>
>>  Why not:
>>
>>  <rdf:Description rdf:about="foo://bar">
>>      <ex:property xsi:type="xsd:integer">10</ex:property>
>>  </rdf:Description>
>>
>>  being defined to parse to:
>>
>  > <foo://bar> ex:property xsd:integer"10" .
>  >
>>  wouldn't this solve much of the datatypes debate -- it would _syntactically_
>>  distinguish typed literals, as Drew McDermott correctly points out is the
>>  way to go, and would avoid issues related to nonmonotonicity related to
>>  interpreting a triple based on a schema that may or may not be present.
>
>This has been proposed several times, by several people, including myself,
>most recently in
>   http://lists.w3.org/Archives/Public/www-rdf-comments/2002JulSep/0024.html
>The RDF Core WG has, for some reason, chosen not to accept this in any
>guise, even as part of a datatyping facility for RDF.

One reason is that (as far as I can see; correct me if Im wrong here) 
this proposal does not allow non-datatyped literals. That (very 
strong) constraint seems unacceptable for RDF and would clash with 
established usage. In a related criticism, it does not (again, please 
correct) allow for 'remote' datatyping, where the association of a 
datatype with a property range imposes a datatype interpretation on 
uses of the property in other statements.

As an example of a problematic inference, consider whether

<foo://bar> ex:property xsd:integer"10" .
<foo://baz> ex:property xsd:octal"12" .

should or should not entail

<foo://bar> ex:property _:xxx .
<foo://baz> ex:property _:xxx .

and how this could be detected by a reasoner.

Pat
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Received on Friday, 19 July 2002 17:21:42 GMT

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