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Re: Mistaken identity?

From: Thomas B. Passin <tpassin@comcast.net>
Date: Mon, 28 Jun 2004 23:00:12 -0400
Message-ID: <40E0DB3C.40207@comcast.net>
To: www-rdf-interest@w3.org

David Menendez wrote:

> Thomas B. Passin writes:
> 
> 
>> The point is, you can't really determine even a namespace to try to
>>  dereference in the hopes of getting some useful information except
>>  by using heuristics that are not specified or sanctioned by the 
>> Rec.
> 
> 
> Who said anything about dereferencing namespaces?

Well, John Hanna (for one) said something exactly like that on
6-24-2004, and IIRC I was responding to his post (or maybe subsequent 
discussions).

He said this -

"There is no fragment identifier within the document obtained from
http://www.w3.org/1999/02/22-rdf-syntax-ns, though I seem to remember
that rdf:ID was once used there (there were still issues in treating
that as a fragment identifier). Still at least dereferencing
http://www.w3.org/1999/02/22-rdf-syntax-ns will tell me that:

<rdf:type> <rdf:type> <rdf:Property> .
<rdf:type> <rdfs:isDefinedBy> <rdf:> .
<rdf:type> <rdfs:label> "type" .
<rdf:type> <rdfs:comment> "The subject is an instance of a class." .
<rdf:type> <rdfs:range> <rdfs:Class> .
<rdf:type> <rdfs:domain> <rdfs:Resource> .

And dereferencing http://www.w3.org/2000/01/rdf-schema will tell me that:

<rdfs:label> <rdf:type> <rdf:Property> .
<rdfs:label> <rdfs:isDefinedBy> <rdfs:> .
<rdfs:label> <rdfs:label> "label" .
<rdfs:label> <rdfs:comment> "A human-readable name for the subject." .
<rdfs:label> <rdfs:domain> <rdfs:Resource> .
<rdfs:label> <rdfs:range> <rdfs:Literal> .

So not perfect by my view of what should be done here (I would tend
against using # to end RDF namespaces anyway) but not bad either."

> The point (as I understood it) was that to learn about the resource 
> identified by <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>, you
>  would dereference that specific URI.
> 

Notice what he said -

"There is no fragment identifier within the document obtained from
http://www.w3.org/1999/02/22-rdf-syntax-ns"

> Note that the resource being queried, 
> <http://www.w3.org/1999/02/22-rdf-syntax-ns>, is not the same as the 
> namespace name, "http://www.w3.org/1999/02/22-rdf-syntax-ns#".

Sure, but because the base URI may and often will be all you have to go
on, people get into talking about hitting the namespace URI as a
surrogate for the actual one.  But you can't be sure of actually parsing
out the right base URI to try that with, at least so far as the formal
RDF specs go.

That's all.  Nothing earth-shaking.

Cheers,

Tom P

-- 
Thomas B. Passin
Explorer's Guide to the Semantic Web (Manning Books)
http://www.manning.com/catalog/view.php?book=passin
Received on Monday, 28 June 2004 22:57:30 GMT

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