Re: URIs: resources and contradictions was: Re: httpRange proposed text

/ "Jonathan Borden" <jonathan@openhealth.org> was heard to say:
| I would say what Joshua said even more strongly (this *is* a core
| principle):
|
| "
| When two people use the same URI to identify a resource _they are
| identifying the same resource_
| "
|
| This is true by definition (indeed an axiom)

I'm not sure how to reconcile your statement that this is
axiomatically true when I believe it is obviously false.

| A:
|
| <http://example.org/car> rdf:type timbl:Document .
| <http://example.org/car> ex:length "1024" .
|
| and
|
| B:
| <http://example.org/car> rdf:type rf:Car.
| <http://example.org/car> ex:length "102" .
|
| rf:Car owl:subClassOf owl:Class .
| rf:Car owl:disjointWith timbl:Document .
|
| now let us assume that "ex:length" is a functional property e.g. that a
| resource may have only one value for this property.
| e.g.
|
| ex:length owl:subPropertyOf owl:FunctionalProperty .
|
| What do we have?

Clear evidence that A and B did not identify the same resource when they
independently chose the name http://example.org/car

| Well we have a few contradictions that's all, we are trying to say that:
|
| "1024" = "102" which is patently false
| and we are also trying to say both that http://example.org/car is both a
| timbl:Document and an rf:Car which is a contradiction if we also say that
| rf:Car owl:disjointWith timbl:Document .
|
| To summarize, a URI always identifies a single resource, regardless of who
| is using the URI and regardless of which claims are made about the resource.

Ah, perhaps I get it after all:

You have a reasoning system that uses URIs as identifiers. Because
that system is incapable of "knowing" anything about a URI other than
the string of characters that comprise it, it is axiomatic that if two
URIs are textually identical, they must mean the same thing.

I think I can understand that.

Is it widely accepted fact that this is a feature of all such
reasoning systems? Perhaps it is, I don't know.

                                        Be seeing you,
                                          norm

-- 
Norman.Walsh@Sun.COM    | To create a little flower is the labour of
XML Standards Architect | ages.--Blake
Sun Microsystems, Inc.  |

Received on Saturday, 3 August 2002 10:09:04 UTC