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 11:28:57 -0600
Message-Id: <p05111b13b9e71713e746@[65.217.30.130]>
To: Brian McBride <bwm@hplb.hpl.hp.com>
Cc: w3c-rdfcore-wg@w3.org

>At 09:29 31/10/2002 +0200, Patrick Stickler wrote:
>
>
>>[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)
>
>No it has not.  Their has been some recent discussion on whether 
>they denote (string,lang) pairs or the union of strings and (string, 
>lang) pairs.  To the best of my recollection, denoting just strings 
>is not a current option.

My current understanding is that they can BE either strings or 
(string, lang) pairs, and that they DENOTE whatever they are. I find 
this slightly weird, since we have no way to talk about the 
components of these pairs that are now in the semantic domain, but 
there you are. It has the side advantage (?) of blocking what would 
otherwise be a valid inference of the form

ex:a ex:p "10"fr .
ex:b ex:q "10"en .
-->
ex:a ex:p _:y .
ex:b ex:q _:y .

Pat


>
>>  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.
>
>Why not?  Surely that depends on whether the value spaces of 
>literals and anyURI's are disjoint.  If literals can denote strings 
>(as you claim they can), and anyURI's are strings, then this is not 
>necessarily a datatype clash.
>[...]
>
>>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!
>
>A reference would be helpful here.  Where does  XSD say that 
>different primitive types must have disjoint value spaces.
>
>It is true that anyURI is not derived from xsd:string, but is that 
>because the value spaces are different, or because there is no facet 
>that would allow exact expression of the value space of anyURI?  The 
>only facet that might be used is PATTERN which requires a regular 
>expression.  If the grammar for anyURI cannot be expressed as 
>regular expression, then anyURI cannot be derived from xsd:string.
>
>Brian


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Received on Thursday, 31 October 2002 12:29:05 EST

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