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Re: Meaning of URIRefs

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Fri, 25 Oct 2002 23:20:22 -0400 (EDT)
Message-Id: <20021025.232022.65665711.pfps@research.bell-labs.com>
To: sandro@w3.org
Cc: www-rdf-interest@w3.org

From: Sandro Hawke <sandro@w3.org>
Subject: Re: Meaning of URIRefs 
Date: Fri, 25 Oct 2002 22:17:47 -0400

> > But why should there be any need to have to agree to a pile of facts just
> > to be able to use a term?  
> 
> If you don't, then you're much less likely to be using the term as
> intended. 

Well, the alternative appears to not use the term at all, and thus have no
possibility of communication.

> > > Isn't there a social convention that you don't use a word except in
> > > accordance with its generally-accepted meaning?  And if you don't know
> > > what meaning is generally accepted, then you don't use the word.  (Of
> > > course there are exceptions, ways to indicate use-without-condfidence,
> > > etc, but I believe this convention is the norm.)
> > 
> > Well, not really, people abuse words all the time.  :-)  Just consider most
> > of the modern US presidents, for example.
> > 
> > There is some indication that natural language works best if its users can
> > at least agree on the denotation of the terms they use.  However, there is
> > absolutely no need to agree on any characteristics of the terms.  For
> > example, you and may both use the term ``the Soviet Union'' without
> > agreeing on any fact about the Soviet Union, even whether it ever has been
> > a country.
> 
> And you think we could have a useful, productive conversation when you
> think "the Soviet Union" means the Soviet Union and I think "the
> Soviet Union" means my coffee pot?

Well, it certainly is possible. 

In any case, I'm not arguing for the necessity of such divergent uses of
the same term.  I'm just arguing against the necessity of including a
particular ``surround'' when simply using a term.

I do expect that most users of a term will want some surround, but would
get that surround by committing to some document that provides the
surround.  This document may, and probably usually would, be the
document where the term is defined, but might be some other document.

> > > On the Semantic Web, in the next few years, how is one to know the
> > > generally-accepted meanings of terms?   
> > 
> > > The proposal I'm advocating is that the we should consider the
> > > "generally-accepted meaning" of a URI-Ref in RDF to be exactly the
> > > meaning that is conveyed by the text at the URI.  
> > 
> > And I'm advocating that the ``generally-acccepted meaning'' of a URI
> > reference need not be so mandated.  If a community wants to provide a
> > ``generally-accepted meaning'' for a URI, it can produce a document
> > formally containing that meaning.  Agents can subscribe to that meaning if
> > they so desire; if they want a different meaning then they can subscribe to
> > another ``commonly-accepted meaning'' or even use their own meaning.
> > Agents that share ``commonly-accepted meaning''s will (probably) work
> > better together, but other groups of agents may need to use a different
> > ``commonly-accepted meaning'' for a particular URI.
> 
> Are you suggesting that one URI-Ref can mean two different things?
> (as in the coffee pot example above)

Well, in general URI references can mean lots of different things.  All
that a logical langauge can do is to cut down the potential denotations of
a term.  For example, the term Russia used to be used for lots of different
things, including the USSR and the Russian Federation.  True communication
involving the term was possible even when the two parties in a
communication meant different things by the term.  

I'm not arguing that this sort of divergence is a good idea, particularly
for agents in the Semantic Web, but it may be useful in some cases.

> Or just that different groups may be aware of different facts about
> it, without actually disagreeing about what it is.   Like you may know
> the SU is something that was formed in 1922 and I may know it was
> broken up in 1990.

Yes, this is also possible, and very common.  I feel that it will also be
common in the Semantic Web.  Not only that, but different users may want to
use contradictory facts about the same term, and, moreover, facts that
contradict the facts in the base document for the term.

> > > I'm not sure what you'd consider the generally-accepted meaning of
> > > "George-Bush-the-lesser".  I guess something like "the one of two
> > > famous people named 'George Bush' who is in some overwhelming sense
> > > less than the other."  It's a wonderful example of an English term
> > > which has the same kind of tainted definition you're worried about my
> > > proposal somehow forcing you to use.
> > 
> > Ah, but this is precisely the point I am trying to make.  The denotation of
> > George-Bush-the-lesser can be determined without accepting any of this
> > ``generally-accepted meaning'', so it is possible for anyone to use the
> > term.  The use can either agree with or disagree with this meaning, but
> > will still be able to communicate.
> > 
> > > Why is it not sufficient that my proposal gives you freedom to pick
> > > whatever taint you want, trading it off against the ease and/or
> > > ability of recognizing when you're talking about the same thing as
> > > what someone else defines differently?    I don't see natural language
> > > doing any better, and that makes me think we can't do any better.
> > 
> > But natural language is indeed doing much better; you are using the term
> > without agreeing to the ```taint''.  Forcing agents on the Semantic Web to
> > accept such taints will, in my opion, place a severe chill on the Semantic
> > Web.
> 
> I was only able to use it without taint by quoting it!

Well, I've been using the term for quite a while without committing to the
taint.  I also don't require that others that use the term commit to the
taint.  And this is for a term that somehow carries the taint in its very
construction.

>     -- sandro

peter
Received on Friday, 25 October 2002 23:20:32 GMT

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