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Re: WEBONT "HOMEWORK" (FOL or class/property)

From: Dan Connolly <connolly@w3.org>
Date: Thu, 06 Dec 2001 12:26:10 -0600
Message-ID: <3C0FB842.3D305036@w3.org>
To: Pat Hayes <phayes@ai.uwf.edu>
CC: "Smith, Ned" <ned.smith@intel.com>, www-webont-wg@w3.org
Pat Hayes wrote:
[...]
> I think
> that as a basic ontology language, DAML+OIL is 'warped' by its being
> a class/property language rather than a conventional logical
> language. For things that are simple and natural to state as in
> class/property terms it is fine, but other kinds of propositions
> require one to introduce very artificial classes defined in terms of
> restrictions in order to state simple facts (and simple queries), and
> the resulting complexities of needing to learn to think in this odd
> way add further barriers to the already considerable difficulties of
> using DAML+OIL.

That's my experience as well.

For example, I have some tools for doing sort of visual stylesheets
for RDF (http://www.w3.org/2001/02pd/) ... stylesheets say things like

	draw working groups using blue circles.

Given my background, it's quite straightforward to phrase that as:

	(forall (?x)
		(=> (WorkingGroup ?x) (and (color ?x 'blue) (shape ?x 'circle))))

and I can twist my head a little to write it in N3:

	this log:forAll :x.
	{ :x a :WorkingGroup } log:implies { :x g:color "blue"; g:shape
"circle"}.

but writing it in DAML+OIL hurts pretty badly:

	:WorkingGroup rdfs:subClassOf [
		ont:onProperty g:color; ont:hasValue "blue"],
		[ ont:onProperty g:shape; ont:hasValue "circle"].

now maybe N3 isn't a very good syntax for DAML+OIL, but
translated back to natural language, we'd get:

	WorkingGroup is a subclass of the class of things
		that have color blue
		and a sublcass of the class of things that
		have shape circle.

which is not how I think. I'm trying to train myself, but
it looks daunting...

> I would suggest something like 
> a 'neat' syntax for FOL - perhaps a subset, eg a constructive or 
> intuitionist subset(?) - with a distinguished typing syntax that is 
> similar in power (though maybe not quite in form) to DAML+OIL, ie a 
> genuine logical extension of DAML+OIL.

I like the idea of constructive/untuitionist subset of FOL appeals
to me, based on my experience and research.

I have also worked a lot with larch, which is a sorted first-order
logic, and the sorts did make the syntax nice.

But this is stretching our charter somewhat. This is the
sort of design I work on in the context of Advanced Development,
not working group stuff, usually. I wouldn't mind if we wanted to
stretch our charter that way, but only if pretty much everybody
else prefers this sort of design too.


-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Thursday, 6 December 2001 13:26:13 GMT

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