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Re: [RIFWG] [Requirements?] A vision for the RIF

From: Michael Kifer <kifer@cs.sunysb.edu>
Date: Mon, 24 Apr 2006 22:49:23 -0400
To: Chris Welty <cawelty@frontiernet.net>
Cc: Francois Bry <bry@ifi.lmu.de>, edbark@nist.gov, public-rif-wg@w3.org
Message-ID: <9956.1145933363@kiferdesk>


Chris Welty <cawelty@frontiernet.net> wrote:
>
> Michael Kifer wrote:
> >> Michael Kifer wrote:
> >>     
> >>> I said that normative rules imply that we must use some sort of a closed
> >>> world assumption. Under the open-world assumption there is no useful way to
> >>> distinguish between normative rules and deductive rules, but under the CWA
> >>> there is.
> >>>   
> >>>       
> >> I am not sure I can agree with this. I can very well imaginbe normative
> >> rules not governed by a Closed World Assumption.
> >>     
> >
> > Francois,
> >
> > The above must be taken in the context of my earlier message
> > http://lists.w3.org/Archives/Public/public-rif-wg/2006Mar/0161.html
> > where I *proved* that the rule set for which those normative rules act as
> > constraints must have some sort of closed world assumption (more precisely,
> > cannot use the normal first-order semantics).
> >   
> 
> I must say that "proved" is a bit strong here.  You have used in your 
> argument a particular definition of constraint that infallibly leads to 
> your conclusion.  For those indoctrinated in the logical school (to 
> paraphrase your term), a constraint can just be an axiom and 
> satisfiability the test.  This is not to say one is right or wrong, just 
> that your argument constitutes no proof.

OK, ok. Of course, I made some assumptions. But to substantiate his claim,
Francois had to provide a similarly rigorous argument, perhaps based on
a different set of assumptions.

Peter provided such an argument based on a different set of assumptions,
although (per my earlier message) I think he didn't succeed in showing that
constraints and regular formulas are somehow different in FOL. In his
example the two sets of formulas are interchangeable.


	--michael  

> 
> > I did not say that normative rules must be "governed" by CWA, because I
> > don't know what this might mean.
> >
> > If you think that my very short proof has a bug then please point this out.
> >
> >
> >
> > 	--michael  
> >
> >
> >
> >
> >   
> 
> 
> -- 
> Dr. Christopher A. Welty                    IBM Watson Research Center
> +1.914.784.7055                             19 Skyline Dr.
> cawelty@frontiernet.net                     Hawthorne, NY 10532
> http://www.research.ibm.com/people/w/welty
> 
> 
> 
Received on Tuesday, 25 April 2006 02:49:29 GMT

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