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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
construct.

> 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
experiences.


> 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?
  http://lists.w3.org/Archives/Public/www-webont-wg/2002Apr/0202.html

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 GMT

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