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RE: Properties of Properties Question

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 24 Oct 2001 07:00:37 -0400
To: www-rdf-logic@w3.org
Message-Id: <20011024070037M.pfps@research.bell-labs.com>
From: "Thomas B. Passin" <tpassin@home.com>
Subject: Re: Properties of Properties Question
Date: Wed, 24 Oct 2001 06:07:55 -0400

> [Dickinson, Ian J]
> > From: Thomas B. Passin [mailto:tpassin@home.com]
> > > Well, the assertion is a triple so once you reify it you can
> > > association information with it by making assertions about the
> > > reified statement.  Isn't
> > > that precisely what reification is for?
> > Yes, that's what I had previously assumed, but if a reified statement is
> > still a statement then it contradicts this claim from Peter
> Patel-Schneider
> > :
> >
> > >> (In RDF terms
> > >> this would probably be using a statement as the
> > >> subject of another
> > >> statement, which can't be done in RDF.)
> >
> > which he re-inforced with the following:
> >
> > >> This can't be done in DAML+OIL
> > >> because assertions cannot have associated information.
> >
> > Hence my confusion.
> Well it's so or not so, depending on how you look at it.  You can't make an
> assertion about the original statement because it does not exist as an
> atomic thing with a node, id, or what have you.  So that's true.  You can
> make an assertion about the reified statement, but that reification is not
> literally the "original" statement, but instead a different one (or a
> different node if you like).

Restated, what you can do is given a statement (triple) <s, p, o> make an
assertion about a resource that belongs to the class Statement, is related
to s via a subject link, to p via a predicate link, and to o via an object
link.  Whether this has anything significant to do with the original statement
(triple) is left as an exercise to the reader, certainly there is only a
very weak (at best) relationship between the two in RDF.

> The reification of the original statement is not actually "a" statement,
> instead it is a package of three [four] of them.  Still, it can be a node in the
> graph.  It would be an anonymous node so far as I can see.  I remember
> seeing illustrations of  making assertions about reifications of statements
> in the M&S.
> Cheers,
> Tom P

Peter F. Patel-Schneider
Received on Wednesday, 24 October 2001 07:01:25 UTC

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