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Re: A plea for peace. was: RE: DAML+OIL (March 2001) released: a correction

From: Dan Connolly <connolly@w3.org>
Date: Thu, 05 Apr 2001 07:32:39 -0500
Message-ID: <3ACC65E7.EB16BD69@w3.org>
To: Aaron Swartz <aswartz@swartzfam.com>
CC: pat hayes <phayes@ai.uwf.edu>, RDF Logic <www-rdf-logic@w3.org>
Aaron Swartz wrote:
> pat hayes <phayes@ai.uwf.edu> wrote:
> > The way to fix RDF is to admit that logical content requires the use
> > of some - maybe not many, but some - nontrivial syntactic
> > constructions, in particular the use of nested expressions and
> > quantifier scoping;
> Isn't this already available in RDF in one form or another?

Only in the way that RSS is available in RDF; i.e. it's
not, but it can be layered on top in various ways.

> > to abandon the idea that syntax is the same as,
> > or best coded using, reification;
> I don't believe anyone ever said syntax should be coded as reification.

Perhaps I did, in a draft and a presentation I gave about it[1].

I started down that path in response to TimBL's toolbox ideas...
I think I talked him into the "not by reification" stuff[2].
He had written up not and forall and such using a pretty
much separate layer altogether.

The idea seems to have gotten out of hand... while I
think there's some value in being able to map RDF-with-logic
into RDF 1.0 syntax, and it has been an interesting
puzzle to explore, I don't expect to use it in
practice much; it turns parsing formulas into theorem-proving.

In practice, I expect rdf-logic agents to just parse
formulas in pretty traditional ways, using just
one syntactic form of the forall, not, symbols etc.

There's considerable evidence that using acyclic
graphs for formula and proof representation has
real utility (cf Soiffer and Necula resp.), and I intend
to continue looking at that idea.

And I think there's a place for reification when
it comes to relating logic to communication protocols
(but I'm not sure about that).

But in practice, I don't expect to use reification
to actually convert between logical formulas
and RDF 1.0 syntax.



Section 3.6 Defining Inference Rules of [SHOE] specifies a form of
horn clause rule with some restrictions on the occurrence of
variables. This format includes rules of the same expressive power,
expressed in RDF normal form.

The Converting SHOE to RDF appendix explains these rules by
showing how to generate them from SHOE syntax.

The version 0.5 draft syntax appendix discusses the syntax for these
rules independent of SHOE. The semantics are based on KIF quoting,
as explained in the appendix KIF as an RDF Schema.

--        An Agent Markup Languagee version 0.5 draft
Wed, 11 Oct 2000 03:30:57 GMT


Not by reification

I am not proposing that the best machine in practice to process the
language we are building is based directly on RDF triplets - but it is
important to ground new features in basic RDF. As RDF has little
power at its basic level, anything new has to be introduced by
reification - by describing it in RDF. 

--        The Semantic Toolbox - on top of XML-RDF - Ideas on Web
Thu, 22 Mar 2001 18:22:15 GMT

> Merely that reification had a precise meaning ("I'm not saying this -- I'm
> talking about it") and that it could be used to encode logical constructs
> without necessarily bringing them into RDF Core.

Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Thursday, 5 April 2001 08:32:43 UTC

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