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Re: Meaning of URIRefs

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Fri, 25 Oct 2002 19:45:28 -0400 (EDT)
Message-Id: <20021025.194528.68555084.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 16:51:30 -0400

[...]

> > Well, all my examples about George-Bush-the-lesser require the use of a
> > well-known identifier for that George Bush.  It sure seems to me that these
> > are all examples of pointers from instance data to other instance data.
> > Just about any appliction of the semantic web that I can think of, from
> > travel planning to phone routing to fully automated assistants, require a
> > network of instance data on multiple sites with many references betwee
> > them.
> 
> I'm not forbidding multiple instance data files from using the same
> URIRef for something.  I'm just trying to help make sure they're using
> it for the same thing by providing a common bit of information about
> it which they all share, which they all agree to in order to use the
> term.

But why should there be any need to have to agree to a pile of facts just
to be able to use a term?  

> 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.

> 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.

> 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.

[...]

peter
Received on Friday, 25 October 2002 19:45:38 GMT

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