W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > October 2002

Re: Datatyping literals: question and test cases

From: pat hayes <phayes@ai.uwf.edu>
Date: Thu, 31 Oct 2002 10:56:43 -0600
Message-Id: <p05111b0cb9e710505171@[65.217.30.130]>
To: "Patrick Stickler" <patrick.stickler@nokia.com>
Cc: w3c-rdfcore-wg@w3.org

>[Patrick Stickler, Nokia/Finland, (+358 40) 801 9690, 
>patrick.stickler@nokia.com]
>
>>  >But, what about this:
>>  >
>>  >   _:x ex:prop "http://example.org/" .
>>  >   ex:prop rdfs:range xsd:anyURI .
>>
>>  That depends on how xsd:anyURI defines its value space. If its the
>>  set of strings conforming to the URI syntax, then OK.
>
>ARGH! Pat, no!
>
>The WG has decided (with Nokia's dissent) that inlined literals
>denote their string components (i.e. string-semantics) and therefore
>the above range assertion is a datatype clash! It is *never* OK.
>Never ever ever. It is not possible for it to ever be OK.

Well, I said that IF xsd:anyURI is a set of strings.... I gather that 
it isn't; OK, then not OK.

>
>If it were to be valid, the literal must be explicitly typed, *always*
>
>    _:x ex:prop "http://example.org/"^^xsd:anyURI .
>
>Furthermore, not that xsd:anyURI is *not* a subtype even of xsd:string!
>I.e., even XML Schema says that a member of the value space of xsd:anyURI
>is *not* a member of the value space of xsd:string -- a URI is not a string!
>
>Now... if we had made the more rational decision to adopt value-based
>semantics for inlined literals, then Jeremy's example would have
>been fine and dandy, with the range assertion providing the interpretation
>of the inlined literal, and all would be well.
>
>But as it is, were stuck with this insane (IMO) string-based
>semantics that makes inlined literals and typed literals forever
>disjunct (even if we call inlined literals 'typed' as members of
>rdfs:StringLiteral or some such datatype).
>
>Inlined literals and rdfs:range will *never* work together, except
>in the single case of rdfs:StringLiteral. I wonder if folks appreciate
>that oddity.

You seem to be assuming that it is impossible for two different 
datatypes to have the same value space. I wasn't aware that this was 
a general rule. I would have no problem for example saying that 
rdfs:StringLiteral and xsd:String had the same value space. (NOt the 
same lexical space, but the same value space.)

Pat

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Received on Thursday, 31 October 2002 11:56:49 EST

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