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Re: Why? Re: rdf as a base for other languages

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Sun, 03 Jun 2001 05:53:26 -0400
To: seth@robustai.net
Cc: www-rdf-logic@w3.org
Message-Id: <20010603055326A.pfps@research.bell-labs.com>
From: "Seth Russell" <seth@robustai.net>
Subject: Re: Why? Re: rdf as a base for other languages
Date: Sat, 2 Jun 2001 15:20:55 -0700

> From: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
> 
> > From: "Seth Russell" <seth@robustai.net>
> > Subject: Re: Why? Re: rdf as a base for other languages
> > Date: Sat, 2 Jun 2001 12:45:16 -0700

[...]

> Well I will leave it to other to argue whether M&S implies that a reified
> statement stands for the statement or not.  But M&S states quite clearly
> that reif[y]ing a statement does not assert it.

The reification of a statement (triple) does not contain the statement
(triple), so does not assert it.  Hopefully I haven't stated otherwise.

> > > Then can you tell me the difference between a
> > > statement having a reified statement as it[]s object and a statement having
> > > the statement itself as it's object?
> >
> > If a statement is the object, then it is asserted.
> 
> Excuse me ..... [1] {says (Jon,  (the sky is red))} asserts that (the sky is
> red) ?   ... I think not!

In RDF, if a statement (triple) appear in the input, then it is asserted.
If it does not appear in the input, then how could it be the object of
another statement (triple)?  [1] above is not RDF.  (Actually, RDF doesn't
allow objects of triples to be triples anyway, but consider the minimal
change required to allow this.)

> > If a resource that has
> > type Statement is the object, then the thing or things that are asserted
> > are quite different.  Consider the RDF data model resulting from the two
> > situations.  They are quite different.
> 
> If we assumes the truth of [1], then we can understand your statement here;
> but if we do not, we see only consusion there.

I had nothing about [1] in my RDF statements (triples), so I don't know how
it is relevant.

> > > Me thinks you draw a distinction that
> > > makes no difference.
> >
> > On the contrary, there is a large difference between pointing to something
> > that asserts a base fact and pointing to something that does not assert
> > that base fact.
> 
> Well certainly, yes,  there is a difference.  Don't forget I was trying to
> show how context can be used such that allowing a statement to be an object
> of an intensionally opaque verb would not assert that statement.  In other
> words your difference is based upon the contradiction of the very solution
> that I propose.  Why would you do a thing like that?

The whole point is that within RDF you cannot have contexts.  I don't know
of any way of doing what you want within RDF.  (Sure if you have some
private meaning for certain collections of RDF triples you can do lots of
stuff.  Consider DAML+OIL as an example.  However, that is not (just) RDF.)

> Seth Russell

Peter F. Patel-Schneider
Received on Sunday, 3 June 2001 05:54:57 GMT

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