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 13:32:52 -0600
Message-Id: <p05111b1bb9e73423b7c5@[]>
To: "Patrick Stickler" <patrick.stickler@nokia.com>
Cc: w3c-rdfcore-wg@w3.org

>[Patrick Stickler, Nokia/Finland, (+358 40) 801 9690, 
>>  >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.
>Not at all. But see below.
>>  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.)
>I am presuming, perhaps incorrectly, that for one value space
>to intersect with another value space that for any two values
>X and Y which occur in the intersection of those value spaces
>the same relations hold for them in terms of either datatype.
>I.e., if X < Y in datatype 1 then X < Y in datatype 2.
>If one datatype has an ordered value space and the other does
>not, then can they really intersect?

Well, what does it mean to say that the space doesn't have an 
ordering? I mean, its not *impossible* to define an ordering on 
URIrefs. I think you have a picture here where a 'space' is something 
like an algebra, ie a set together with some operations or relations 
on the set, rather than simply a set or class of things. Two 
different algebras can have the same underlying set. (I think its 
called the 'carrier' of the algebra, but it was years ago :-)

>If X = Y in one value space yet X != Y in the other value space
>can they really intersect?

Well, not if that really means identity, but then if it meant that, 
this would be impossible.

>I think not, in both cases.
>Since I do not consider the value space of rdfs:StringLiteral
>to be ordered, then I do not see that it can intersect with
>that of xsd:string.

HOw about saying that xsd:string has an ordering defined on it which 
isnt relevant to rdfs:StringLiteral?

The reason for being so careful about this terminology is that the 
operations are defined on the whole space, sure; but the things IN 
the space are just what they happen to be, which ever category you 
put them into. So with the operations-over-the-carrier-set picture, 
any particular rdfs:StringLiteral is indeed an xsd:string and vice 
versa, even if it makes sense to distinguish the two classes for some 
'global' reason.

This is the 'weak typing' view Im giving you here, of ocurse.

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Received on Thursday, 31 October 2002 14:33:05 UTC

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