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Re: reification test case

From: Seth Russell <seth@robustai.net>
Date: Wed, 6 Feb 2002 20:18:20 -0800
Message-ID: <017701c1af8e$79e433e0$657ba8c0@c1457248a.sttls1.wa.home.com>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: <www-rdf-logic@w3.org>
In response to "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>

Let me clean this up a bit and start fresh not using the word 'refer';  it's
tripping us up.

RDF is used to describe resources, right?   Bnodes describe resources.   The
use of the word 'single' is what we are arguing about.  Certainly Bnodes do
not necessarily describe only a *single* object in the domain of our
discourse.  One Bnode can describe many objects at once.   For example:  the
following RDF Bnode description, written in N3 with it's corresponding
schema (not included), certainly does not describe only one *single*
automobile.

   [rdf:type :Automobile;
    :has :wheels, :motor; :
    :manufacturedBy :GM;
    :modelName "Oldsmobile"]

Does the MT say differently?

Now if that description were of a statement and not of an automobile, would
the new MT suddenly force that node to describe only one *single* statement
?   I think not.

Now continuing with:

Example [A]:
<rdf:description>
<rdf:type>:Statement</rdf:type>
<rdf:subject>:Gore</rdf:subject>
<rdf:predicate>:wonThe</rdf:predicate>
</rdf:description>
which describes all statings that use the same triple.

Example [B]:
<rdf:description>
<rdf:type>:Statement</rdf:type>
<rdf:subject>:Gore</rdf:subject>
<rdf:predicate>:wonThe</rdf:predicate>
<dc:author>:Seth</dc:author>
</rdf:description>
which describes only those which use that triple and which were written by
me.

Peter Patel-Schneider said:

The point is that you seem to be aiming toward the view that there is some
difference in essence between the RDF meanings of the two resources just
above.  The two things above are just resources, nothing more, nothing less.
They are the subject of several RDF statements (three for the first and five
for the second), one of which is given a slight bit of extra meaning by
RDFS, but nothing to indicate that there is a type/token distinction between
them.

[and then explaining the type/token distinction]

The domain of discourse is a collection of objects or tokens.  There are
collections of these objects that form useful groups, which we will call
classes or types.  The two are disjoint.  Tokens have properties.  Types
don't have properties.

Seth continues:

Ok, using your terms and meanings above:   there is no type\token
distinction between the resources described differentially by examples [A]
and [B] above.  [A] and [B] describe, either both objects, or both tokens ..
depending on what the WG decides.  Now I would prefer to interpret them as
describing tokens which would allow RDF to describe things in it's own
syntactic domain.  But the WG could just as easily interpret them as
describing the event objects of statings.  Either way is fine with me, and
either way might have interesting side effects.

Seth Russell
Received on Wednesday, 6 February 2002 23:22:07 GMT

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