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Re: Denotation of URIs

From: Seth Russell <seth@robustai.net>
Date: Fri, 11 Apr 2003 09:16:54 -0700
Message-ID: <3E96EA76.2050402@robustai.net>
To: Patrick.Stickler@nokia.com
CC: pfps@research.bell-labs.com, www-rdf-interest@w3.org

Patrick.Stickler@nokia.com wrote:

>>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.

Yes, I totally agree.  

>>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.

Uuh ... that is not a true statement.  If someone (or even in the future 
some software agent) wisely uses the kind of human reasoning that people 
are accustomed to use with natural language, they should know that their 
"atomic primitives" need not necessarirly 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

I agree,  "unambigous denotation of URIs" (U) and "what kind of logic 
you use" (L) are two separate things.  I am just saying that to the 
extent that you trust that you  have U,  then you can use a strong L 
(like for instance one where A==A), to the extent that you do not trust 
U or even find that it leads to contradictions, you should use something 
else.   The fact is, and hopefully you will agree with me here, 
everybody in the world  is just not going to use a URI to denote the 
same thing across the board and in all cases;  and to assume that they 
will is going to sort out to be just down right stupid.  The idea that 
they *should* always denote the same thing is like the idea that 
everybody *should* always obey the law.  

I believe that the mentograph below does express that quite usefully.


Seth Russell
Received on Friday, 11 April 2003 12:17:06 UTC

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