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Re: semantics and RDF(S)

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Fri, 12 Jan 2001 09:51:07 -0500
To: danbri@w3.org
Cc: www-rdf-logic@w3.org
Message-Id: <20010112095107X.pfps@research.bell-labs.com>
From: Dan Brickley <danbri@w3.org>
Subject: Re: semantics and RDF(S)
Date: Fri, 12 Jan 2001 09:34:17 -0500 (EST)

> Peter,
> On Fri, 12 Jan 2001, Peter F. Patel-Schneider wrote:
> > In the process of working on the design of DAML+OIL, I have had extensive
> > dealings with RDF and RDF Schema.  In this message I present the biggest
> > problem that I see with RDF and RDF Schema.
> > [...] How can I build a notion of cardinality
> > when there is no notion of equality for much of RDF and RDF Schema?
> In the process of working on and with RDF, similar issues have bothered
> me. Most specifically, concerns surrounding our notion of identity,
> resource naming and the connection between URIs and the things they
> supposedly name.
> [...]
> Dan

I agree that there needs to be a notion of identity for web resources, and
that RDF may not the ideal place to discuss it.  However, there is much
less need for this notion in other W3C forums, so the discussion may have
to be started here.

The notion of what is a web resource and the role of its name (as a URI)
is, as expected, rather complex.  The only point that I would like to make
now is that there is no way that we can use the ``unique name assumption''
when working with the web.  (The unique name assumption states that
different names are names for different objects.)   The reason for this is
that there is a many-to-one map from URIs to web resources.  (For example,
http://w3.org and http://www.w3.org point to the same web page.)

My main concerns with RDF, however, live on a different level than this.
Suppose that we nailed down the notions of identity and equality for ``web
resources''.  Then there still is a problem with identity and equality for
RDF resources, such as bags.  

Peter Patel-Schneider
Received on Friday, 12 January 2001 09:51:23 UTC

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