# Re: Layering LX (or FOL) on RDF

From: Sandro Hawke <sandro@w3.org>
Date: Tue, 27 Aug 2002 04:13:49 -0400
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>

```
> From: Sandro Hawke <sandro@w3.org>
> Subject: Re: Layering LX (or FOL) on RDF
> Date: Mon, 26 Aug 2002 21:25:26 -0400
>
> [...]
>
> > > > I'm proposing that the logical formula
> > > >
> > > >     % there exists a triple whose subject is itself
> > > >     exists t subjTerm predTerm objTerm pred obj (
> > > >       rdf(t, lx_subjectTerm, subjTerm) &
> > > >       rdf(subjTerm, lx_denotation, t) &
> > > >       rdf(t, lx_predicateTerm, predTerm) &
> > > >       rdf(predTerm, lx_denotation, pred) &
> > > >       rdf(t, lx_objectTerm, objTerm) &
> > > >       rdf(objTerm, lx_denotation, obj)
> > > >     )
>
> [...]
>
> > > > has the same meaning as any other formula which contradicts the
> > > > layering axioms or contradicts itself, such as
> > > >
> > > >      % there exists some triple which is both true and false
> > > >      exist a b c (
> > > >        rdf(a,b,c) & -rdf(a,b,c)
> > > >      )
> > >
> > > Again, what logical formula is this supposed to be?
> >
> > It's a way of saying (p & -p), but I'm restricting myself to the LX
> > subset of FOL where at the moment I'm only allowing one predicate, the
> > ternary "rdf".  I don't think this restriction has any serious
> > utility, it just made defining the language's relationship to RDF
> > easier.
>
> Sorry.  My point was more that the formulae themselves, if read
> literally, don't seem to match up with the comments attached to them.

You mean the comment should have been more like

"There is something which has an lx_subjectTerm property which
is something which has an lx_denotation property which is the
first thing."   (I realize now the last four triples are are
superfluous to my example.  One could phrase it even more literally
in terms of an "rdf relation", of course.)

and

"Some false proposition is true"

?

Yeah, I probably should have had both kinds of comments there.

Do you have more thoughts on meat of the previous message, clarifying
whether we can do same-syntax semantic extension from RDF to FOL?

-- sandro
```
Received on Tuesday, 27 August 2002 04:14:36 UTC

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