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Re: Layering LX (or FOL) on RDF

From: Seth Russell <seth@robustai.net>
Date: Tue, 27 Aug 2002 11:15:43 -0700
Message-ID: <00a401c24df5$c2c96520$657ba8c0@c1457248a.sttls1.wa.home.com>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: <sandro@w3.org>, <www-rdf-interest@w3.org>

From: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>

> From: "Seth Russell" <seth@robustai.net>
>
> > From: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
> >
> > > Well, how does one forbid self-referencing sentences.  To do so, one
would
> > > have to say something like
> > >
> > > _:s rdf:type rdf:Statement .
> > > _:s rdf:subject _:s .
> > >
> > > is not an RDF graph.
> >
> > It seems to me that  "_:s rdf:subject _:s"  is not a self referencing
> > triple.  In fact I dont's see how you could even write a self
referencing
> > triple in RDF at all, since RDF does not even provide for triples to
have an
> > identity.  In the example above "_:s" is the identity of the thing of
type
> > Statement, not the identity of the triple.
> >
> > Help, I'm confused  ?
> >
> > Seth Russell
>
> Hmm.  You have a point here.  You would not have to use RDF reification at
all.
>
> However, suppose you have a way of representing formulae in RDF.  This
will
> have to use resources and statements.  When you represention ~p, you will
> have to have an RDF graph with a resource for the formula p and another
resource
> for the formula ~p.  How can you allow this, and forbid the RDF graph that
> is your RDF graph for ~p except that it replaces the resource for p with
> the resource for ~p?

I don't understand your paragraph.   p is not a formula ... can never be a
formula, in my view.  Doesn't "p" just identify a node or represent a
resource?  {p negation ~p} is a formula.   I would represent negation,
conjunction, and disjuntion formula as per this mentograph:

http://robustai.net/mentography/negation_conjunction_disjunction.gif

What is the problem again with these kind of arrows ?

<snipping stuff who's complexity I do not understand>

> Truth and falsity are represented by inclusion in the classes pl:Truth and
> pl:Falsity, respectively.

Ok, the pink resources (which are formula) can be of of rdf:type pl:Truth or
pl:Falsity relative to some other graph.

> To forbid self-reference, you have to *forbid* RDF graphs that contain
> things like
> _:x pl:negation _:x .

I have no problem with calling that formula rdf:type pl:Falsity relative to
any graph that purports to be binarilay logical.  But I dont' know if we
must forbid it, I mean anybody can say anything about anything ... can't
they?

Seth Russell
http://robustai.net/sailor/
Received on Tuesday, 27 August 2002 14:16:39 GMT

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