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RE: Denotation of URIs

From: <Patrick.Stickler@nokia.com>
Date: Fri, 11 Apr 2003 09:04:28 +0300
Message-ID: <A03E60B17132A84F9B4BB5EEDE57957B01B90CC0@trebe006.europe.nokia.com>
To: <seth@robustai.net>
Cc: <pfps@research.bell-labs.com>, <www-rdf-interest@w3.org>

> -----Original Message-----
> From: ext Seth Russell [mailto:seth@robustai.net]
> Sent: 10 April, 2003 21:21
> To: Stickler Patrick (NMP/Tampere)
> Cc: pfps@research.bell-labs.com; www-rdf-interest@w3.org
> Subject: Re: Denotation of URIs
> Patrick.Stickler@nokia.com wrote:
> >I just don't see how it is possible to reconcile the two views
> >that (a) ambiguity of denotation is bad and should be avoided,
> >eliminated, fixed and (b) ambiguity of denotation is fine and
> >acceptable.
> >
> Ambiguity of denotion is bad relative to what?  

Reliably communication. I.e. consider a recent example

If the URI being used to denote who the first lady
is, is being used ambiguously, then there is no way to actually
test for any disagreement. I.e., I may assert that _:a denotes
Jane and she lives at address X, but that _:b denotes Betty and
she lives at address Y. If you use _:a to denote Betty and assert
that Betty lives at address X, I will see no contradiction, because
according to my understanding of _:a you are saying that Jane lives
at address X!

So, disagreement about what a URI denotes prevents reliably
communication and even the ability to know if different folks
disagree about various things.

> Now I agree it is bad 
> relative to binary logic ... in fact I believe that binary 
> logic cannot 
> cope with that ambiguity ... am I correct in that belief?  

I think you are, but that is not an expert (as in mathematician's) opinion.

> But such 
> ambiguity is not necessarily bad relative to 3 state logic where the 
> third state is interperted as "Surprise" or "Error" and that state  
> tells us that the law of the excluded middle cannot be applied in the 
> current context.  Is 3 state logic not a possible way out of 
> this morass ?

I don't think that the unambigous denotation of URIs has anything (directly)
to do with binary vs. 3 state logic.

Regardless which logic you use, your atomic primitives must be consistent.

The inferences you make, by whatever logic, based on assertions *using*
those atomic primitives is separate issue entirely. 

URIs are the atomic primitives of the SW, and whatever model of logic you
might apply to interpeting assertions expressed in RDF and infering new
knowledge, those URIs should have globally consistent, unambigous



Patrick Stickler, Nokia/Finland, (+358 40) 801 9690, patrick.stickler@nokia.com
Received on Friday, 11 April 2003 02:04:32 UTC

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