W3C home > Mailing lists > Public > public-rif-wg@w3.org > February 2007

Re: ACTION-219: review of CORE (more)

From: Michael Kifer <kifer@cs.sunysb.edu>
Date: Mon, 12 Feb 2007 16:39:06 -0500
To: "Ginsberg, Allen" <AGINSBERG@imc.mitre.org>
Cc: public-rif-wg@w3.org
Message-ID: <9350.1171316346@cs.sunysb.edu>

>  Hi Michael,
> I am just playing devil's advocate here.  
> > Is it really that simple? 
> Nothing is simple!

You didn't divulged too many details, but if what you are proposing makes
any sense, then a large number of idiots has been working on the problem
for 40 years for nothing. This includes John McCarthy, Vladimir Lifschitz,
Mel Fitting, Ray Reiter, and I just scratched the top of the list.

(Sorry for the sarcasm.)

> > - What does it mean to "make an assumption"?
>    To assume P is to add P to the current reasoning context.
> > - What is the model theory of "making an assumption"?
> There is no model theory of "making an assumption", nor is there a need
> for one: what propositions to take as true in a given context can often
> be a matter of pragmatics, not a concern for semantics.  Semantics
> tells you what follows from the assumptions you have made.

Hmm. So, what does P |= answer mean then, where P is a ruleset?

> > In what sense what you have in mind is more classical than, say, the
> > stable model semantics?
> As far as I understand it, stable model "semantics" is basically a
> procedural add-on to classical semantics involving an implementation of
> the closed-world-assumption.  It is, if you will, a way of implementing
> the assumption that everything that you know nothing about is false.
> Classical semantics makes no such assumption.

Your understanding doesn't come from reading papers on this subject then.
Or, if it does then you completely misunderstood these papers.

> > What if you have recursion through negation?
>  	Abandon ship!

Do you have a spare life jacket?  Hope not another Titanic :-)

Received on Monday, 12 February 2007 21:39:20 UTC

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