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

From: Seth Russell <seth@robustai.net>
Date: Sat, 2 Jun 2001 15:20:55 -0700
Message-ID: <009601c0ebb2$4b86b7c0$b17ba8c0@c1457248a.sttls1.wa.home.com>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: <www-rdf-logic@w3.org>
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
>
> > From: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
> >
> > > I'm sorry but I do not see the ability to define and use contexts in
RDF
> > at
> > > all, nor do I see the ability to have an arc (triple) to be the object
of
> > > another arc, even with reification.  Remember the only thing that RDF
says
> > > about reified statements (i.e., resources with rdf:type rdf:statement)
is
> > > that they have exactly one rdf:subject, one rdf:object, and one
> > > rdf:predicate.
> >
> > Interesting!   I take it you are aware that a triple must be unique (at
> > least in an idealistic sense) in that each of it's component parts are
> > guaranteed to be unique by virtue of the URI system.
>
> Yes, triples are unique, according the Formal Model of RDF, in that there
> can only be one triple with the same three parts.  Yes, the component
parts
> of a triple are uniquely determined by the triple.
>
> > And that you are aware
> > that we can construct a symbol (which symbol is the riefied statement)
that
> > stands for exactly one and only one triple, and if that that symbol can
be
> > an object of a RDF statement.
>
> This is where I disagree.  The four triples
>
> <RDF:predicate,r,p>
> <RDF:subject,r,s>
> <RDF:object,r,o>
> <RDF:type,r,RDF:Statement>
>
> don't stand for anything in the Formal Model of RDF, except the four
> triples.  Yes, there is wording in the Formal Model of RDF (point 9) that
> calls r the reification of the triple <p,s,o>, but there is no impact of
> this in the model.

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 reifing a statement does not assert it.

> > 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!

>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.

>
> > 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?

Seth Russell
Received on Saturday, 2 June 2001 18:25:20 GMT

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