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>

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 :-) --michaelReceived on Monday, 12 February 2007 21:39:20 UTC

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