Re: reification test case

From: "Seth Russell" <seth@robustai.net>
Subject: Re: reification test case
Date: Wed, 6 Feb 2002 20:18:20 -0800

> 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"]

No, no, no, a thousand times no!!!!

One Bnode refers/denotes/... only one thing at a time.

Look, a Bnode is just like the indefinite article.  The above is just like

      an Automobile manufactured by BM with model name Oldsmobile ...

You wouldn't say that *this* refers to more than one car at one time, would 
you?

Of course, the above can describe many different automobiles, but the
operative word is *can*.  Also, English being the wonderful but sloppy
language that it is, you can be sloppy and say that the above describes the
collection of such automobiles.  *However*, this is being sloppy.  To see
how sloppy it is, can you attach properties to the above resource like
cardinality, average price, sales rate, ...?  If you can't, then you should
*not* think of the above resource as a collection of any kind, nor should
you think of it as describing many objects at once.

> Does the MT say differently?

The MT absolutely says that a Bnode refers/denotes/... a single resource.
It does not use the word ``describe'' in connection with Bnodes at all.

> 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.

Well, given that the MT says that all Bnodes refer/denote single resources,
obviously it does.

> 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.

No, this is not part of the RDF MT, and not even part of the intent of RDF,
at least so far as I can decipher the intent of RDF.

> Seth Russell

I fail to see how you think that a Bnode can mean a collection.  I don't
see any support for this view in any RDF document.

Peter F. Patel-Schneider

Received on Thursday, 7 February 2002 07:53:48 UTC