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

Re: The place of rdfs:Literal's in the world...

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Mon, 29 Apr 2002 09:50:26 -0700
Message-Id: <p05101501b8f328d2f3b9@[65.212.118.251]>
To: Patrick Stickler <patrick.stickler@nokia.com>
Cc: w3c-rdfcore-wg@w3.org
>On 2002-04-29 11:05, "ext jos.deroo.jd@belgium.agfa.com"
><jos.deroo.jd@belgium.agfa.com> wrote:
>
>
>>  (the things are called 'resources', but no assumptions are made about
>>  the nature of resources.)
>
>Are all 'resources' in the MT members of rdf:Resource?

Yes. That is, rdf:Resource denotes the universe IR in any interpretation.

>If so, then literals are members of rdf:Resource, right,

NOt necessarily, as the MT is currently set up. (We could do it 
differently so that all interpretations were required to contain all 
strings, but there doesnt seem to be any need for that.)

>  in
>which case, rdfs:Literal should be rdfs:subClassOf rdfs:Resource,
>right?
>
>If all 'resources' in the MT are not necessarily members of
>rdf:Resource, then some further clarification is needed.
>
>>  For example, a triple of the form
>>
>>  <ex:a> <rdf:type> <rdfs:Literal> .
>>
>>  is legal even though 'ex:a' is a uriref rather than a literal.
>>  What it says is that I(ex:a) is a literal, ie that the uriref
>>  'ex:a' denotes a literal.
>
>This seems to conflict with what the Schema spec says, which
>is that a member of rdfs:Literal is self-denoting.

Does it say a member of rdfs:Literal, or a literal?

>A uriref
>is not self-denoting and therefore cannot be a member of
>rdfs:Literal.

A uriref isn't, sure. But (1) a uriref isnt the same thing as a 
resource, and (2) the issue is whether the resource referred to is in 
that class. RDF doesnt have any way of talking about urirefs: it uses 
urirefs to talk about resources.

>
>Do we have a conflict here between the graph syntax and
>the general semantics of RDF Classes?

I don't think so.

>Perhaps rdfs:Literal is not an rdfs:Class?

Well, Im assuming it is a class, so it can't be the set of literals. 
That is my point. If y'all want it to actually be the set of 
literals, then we would need to re-think this whole issue.

Pat
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Received on Monday, 29 April 2002 12:50:13 EDT

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