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Re: ACTION: task force unasserted triples

From: Dan Connolly <connolly@w3.org>
Date: 24 Apr 2002 11:26:10 -0500
To: Pat Hayes <phayes@ai.uwf.edu>
Cc: www-archive@w3.org
Message-Id: <1019665571.17367.117.camel@dirk>
[copy to www-archive, not www-webont-wg; i.e. feel free
to show this to anybody you like, but I don't think
it's worth the WG's time...]

On Tue, 2002-04-23 at 12:14, Pat Hayes wrote:
> The situation can be summed up as follows.

This just looks like hand-waving and appeal to Authority,
not an actual technical argument.

Not to say that the burden of persuasion is necessarily
on you; but if you're trying to persuade me, this doesn't
do it. I would like to understand the technical argument.

> The WebOnt language is 
> obliged by the layering requirements

which layering requirements? Definite descriptions
without clear referents don't help much.

> to treat its own syntactic 
> constructions

What do you mean by 'syntactic constructions' here?
By my reckonning, the syntactic constructions of
WebOnt are exactly the same as those of RDF:

  terms: literals, bnodes, and URIref names
  atoms: S P O triples.
  formulas: conjunctions of atoms.

Please give an example of what you mean by syntactic

> as assertions of the existence of a class corresponding 
> to the syntactic construct(and in fact of a great deal else as well, 
> eg lists). This is because the RDF meaning of the RDF encoding of 
> every piece of the WebOnt language amounts to an assertion of the 
> existence of that class.

Quite. That's by design, and seems quite natural to me.

> And, as Peter has shown, such a requirement 
> is very dangerous,

He has shown that it *can* be very dangerous.
He has not shown, to my satisfaction, that it
is must be dangerous in every case; that
there is no design that avoids the problems.

> since it can rapidly lead to paradoxes or 
> contradictions of various well-known kinds when the language is 
> reasonably expressive. (It may be worth emphasizing that the kind of 
> problems that Peter is talking about have been well-known now for 
> close to a century, are widely studied, and that there is no easy or 
> cute way to hack around them. Some very smart people (Hilbert, 
> Russell, Church, Turing, Goedel, Quine, Kripke, Montague) have 
> wrestled with these problems, and the consensus seems to be that 
> there isn't any way to avoid them.

Look, if it's that well-studied, just spell out (or at
least point to) the argument. An appeal to authority
only makes me more suspicious of your position;
recall our exchange about orthodoxy and Des-Cartes

> Certainly they cannot be avoided 
> by appeals to other kinds of logic, such as multi-valued logics or 
> abandoning the law of excluded middle. They have the same kind of 
> status in foundations of mathematics as, say, the conservation of 
> energy has in physics. A blithe confidence that some way will be 
> found to hack around them should be treated rather like a patent 
> application for a perpetual-motion machine: its really not worth 
> getting into the details of what is wrong with it.)

Meanwhile, you found it worthwhile to read and criticize
Jeremy's attempt to do exactly this, no?

That criticism doesn't seem to say that it's hopeless to
persue this line of work.

I don't understand how to reconcile your messages.

Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Wednesday, 24 April 2002 12:26:01 UTC

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