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RE: DTTF: summary (gasp!)

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Thu, 23 May 2002 14:51:28 +0100
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: <jonathan@openhealth.org>, <www-webont-wg@w3.org>
Message-ID: <JAEBJCLMIFLKLOJGMELDEEAGCEAA.jjc@hplb.hpl.hp.com>
(Short message, with long PS)

Both Peter and Jim ask me to expand a bit, which isn't really somewhere
I want to go.

Suggested change
================

I think a useful way of saying why DTs help solve the problem is:

....
Mainstream Description Logic research is paradox free.
Description Logic makes a distinction between the A-Box and the T-Box.
We will use darkness to identify the T-Box; whereas A-Box semantics will
extend RDFS semantics.
....


This still isn't enough to fully satisfy me (see below), but may be
enough to help DanC!

Jeremy



PS (longer)

I believe that my analysis of the problem is sufficiently off from the
rest of the DTTF that trying to integrate it is not valuable,
particularly since I buy the conclusion.


Basically the three conditions that Jonathan identifies:

1) all RDF triples to be asserted i.e. "truths"
2) classes as instances
3) OWL's need to support commonsense entailments

should, in my opinion, be augmented with a fourth,

4) the state of the art in description logic

and I do not find the arguments about paradox compelling.
(I see each of these as a contradiction rather than a paradox).
The argument from paradox is essentially the only argument Jonathan
gives.

I see the perpetual motion machine quote as a derogatory misreading of
standard computer science practice of maximally using any mechanism that
you are building in its own construction:

[[

This idea of a self-extending language that can, in
principle, describe extensions to itself and then in some sense
become those extensions, like a railway locomotive laying its own
tracks ahead of itself, is a powerful vision, and one that I can see
might excite considerable enthusiasm.  However, so is a
perpetual-motion machine, and for much the same reasons.

]]

But given the state of the art in DL, I think that Peter has adequately
shown that my attempts at comprehensive entailment were research rather
than development, but I am not yet convinced that they were
fundamentally misguided research.

If the argument from paradox is correct and the perpetual machine jibe
is fair then the goal of the comprehensive entailments work is mistaken.
I understand Peter, Pat and Jonathan as believing that; I still don't.
It's a difference. I don't think we need to loose sleep over it. It
will, in my view, be adequately conveyed by an abstention. Also, the
only real way to substantiate my position is to do the necessary
research.

I think my position (#4 above) does make it easier to articulate why
dark triples help solve the problem.
Description Logic makes a distinction between the A-Box and the T-Box;
we have tried and failed to remove this distinction while not "doing
research". We will use darkness to identify the T-Box; whereas A-Box
semantics will extend RDFS semantics.
Received on Thursday, 23 May 2002 09:51:45 GMT

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