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

----- Original Message -----
From: "Norman Walsh" <Norman.Walsh@Sun.COM>
To: <www-tag@w3.org>
Sent: Friday, August 02, 2002 3:37 PM
Subject: 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 19:07:26 UTC