Re: BLD: two issues with the BNF

I fixed the math English, but this still leaves some unpleasant effect - both
in BNF and in the math syntax. For instance, the fact in Example 1 is *wrong*
because facts are required to be universally quantified. So, if it does not
have variables then it should be

Forall (cpt:sell(ppl:John bks:LeRif ppl:Mary))

So, we should either allow ground facts in addition to rules and universal
facts or write everything wrapped in Forall (which is not really nice).


	--michael  

On Fri, 11 Jul 2008 12:44:47 -0400
"Boley, Harold" <Harold.Boley@nrc-cnrc.gc.ca> wrote:

> We say
> (http://www.w3.org/2005/rules/wiki/BLD#EBNF_for_the_Rule_Language):
> If a CLAUSE in the RULE production has a free (non-quantified) variable,
> it must occur in the Var+ sequence.
> 
> Harold
> 
> 
> -----Original Message-----
> From: public-rif-wg-request@w3.org [mailto:public-rif-wg-request@w3.org]
> On Behalf Of Jos de Bruijn
> Sent: July 11, 2008 1:38 PM
> To: kifer@cs.sunysb.edu
> Cc: RIF
> Subject: Re: BLD: two issues with the BNF
> 
> 
> 
> 
> Michael Kifer wrote:
> > On Fri, 11 Jul 2008 09:29:54 +0200
> > Jos de Bruijn <debruijn@inf.unibz.it> wrote:
> > 
> >>>> The second issue is not an error, but it can be considered
> misleading 
> >>>> (the BNF is too liberal): in the presentation syntax, rules are 
> >>>> quantified rule implications.  So, an atomic formula is not a rule
> and 
> >>>> may thus not be directly included in a group.  According to the
> BNF, an 
> >>>> atomic formula can be considered a rule; this is misleading.
> >>> There was a mistake in the math syntax. Groups should also allow
> atomic
> >>> formulas. Fixed.
> >> One more thing: atomic formulas can also contain variables.  I guess 
> >> that such non-ground atomic formulas should not be allowed in groups?
> > 
> > I see no reasons why such formulas should be disallowed. They are
> allowed as part of the KB, so why disallow them in groups?
> 
> 
> I thought all variables in BLD need to be explicitly quantified?
>

Received on Friday, 11 July 2008 19:37:33 UTC