W3C home > Mailing lists > Public > public-rif-wg@w3.org > May 2010

Re: Summary: Urgent: Issue with RIF-Core EBNF Grammar?

From: Jos de Bruijn <jos.debruijn@gmail.com>
Date: Wed, 12 May 2010 14:17:09 +0200
Message-ID: <AANLkTikkLW1LhJlD0Ve_eC0_rs2RuPmUG0r5D7ZcOlzF@mail.gmail.com>
To: Axel Polleres <axel.polleres@deri.org>
Cc: Christian De Sainte Marie <csma@fr.ibm.com>, Dave Reynolds <dave.e.reynolds@googlemail.com>, RIF <public-rif-wg@w3.org>
Going for 2 seems problematic, since it would mean Core is not a subset of PRD.
However, if we would go for 2, I don't an issues with universal facts,
since they are not allowed to have variables (by safeness [1]).

In any case, let me repeat the wording I proposed that fits with option (1):

* Equality terms and class membership terms *cannot* occur in
universal facts, variable-free atomic formulas outside of rule
premises, or rule conclusions -- they are allowed only in rule
premises.

The corresponding wording fitting for option (2):

* Equality terms *cannot* occur in universal facts, variable-free
atomic formulas outside of rule premises, or rule conclusions -- they
are allowed only in rule premises.
* Class membership terms *cannot* occur in rule conclusions -- they
are allowed only in facts and rule premises.

That said, I guess option (2) is a non-starter for most people, as it
takes Core beyond PRD.


Cheers, Jos

[1] http://www.w3.org/2005/rules/wiki/Core#Safeness

On Wed, May 12, 2010 at 1:59 PM, Axel Polleres <axel.polleres@deri.org> wrote:
>
> So, it seems we have two options:
>
> 1) rather painless, but contradicting the group's original resolution, i.e.
>   accept the rewording suggested by Jos [1] to clarify 2.3.
>
> 2) stick to the resoultion, by either adopting c) or d) from [2] (the resolution [3] is not clear about whether
>   universal facts should be allowed or not) and fix both 2.3 and the EBNF grammar.
>
> As I understand it, going for 1) needs at the very least a new group resolution that
> overcomes the original resolution [3] (if that path is chosen, I would kindly ask to record my abstention)
>
> Axel
>
> 1. http://lists.w3.org/Archives/Public/public-rif-wg/2010May/0057.html
> 2. http://lists.w3.org/Archives/Public/public-rif-wg/2010May/0052.html
> 3. http://www.w3.org/2005/rules/wg/meeting/2009-01-15#resolution_3
>
> On 12 May 2010, at 12:31, Christian De Sainte Marie wrote:
>
> >
> > The resolution about membership in Core is recorded here: http://www.w3.org/2005/rules/wg/meeting/2009-01-15#resolution_3
> >
> > It was, indeed, to allow membership in Core facts and conditions.
> >
> > Cheers,
> >
> > Christian
> >
> > IBM
> > 9 rue de Verdun
> > 94253 - Gentilly cedex - FRANCE
> > Tel. +33 1 49 08 35 00
> > Fax +33 1 49 08 35 10
> >
> >
> >
> > From: Dave Reynolds <dave.e.reynolds@googlemail.com>
> > To:   Jos de Bruijn <jos.debruijn@gmail.com>
> > Cc:   Axel Polleres <axel.polleres@deri.org>, Christian De Sainte Marie/France/IBM@IBMFR, RIF <public-rif-wg@w3.org>
> > Date: 12/05/2010 12:09
> > Subject:      Re: Urgent: Issue with RIF-Core EBNF Grammar?
> >
> >
> >
> >
> > On 12/05/2010 09:36, Jos de Bruijn wrote:
> > > Axel, Christian, all,
> > >
> > > I raised my concerns about the RIF-Core spec in a separate email.
> > >
> > > Concerning facts about class membership: they are both in BLD and PRD
> > > (see [1]).
> > > Concerning class membership atoms in rule conclusions: I do remember
> > > that we explicitly forbade them in Core.
> >
> > That's my recollection too.
> >
> > Our official record of the decision [1] was to allow membership "in Core
> > facts and conditions".
> >
> > We did at one point have an EBNF that reflected that resolution.
> >
> > My memory [2] was that Gary on behalf of the PRD group later pointed
> > that asserting membership facts was just as problematic as concluding
> > them via non ground rules. The problem being that in object-based PR
> > implementations membership is hardwired in the external data model. So
> > we decided to forbid any assertion of membership facts. I.e. the EBNF
> > accurately reflects our intention[3].
> >
> > The phrasing in section 2.3 is clarified by "they [equality terms and
> > class membership terms] are only allowed in rule premises". I agree that
> > the term rule "premise" is not defined in the document so it could be
> > clearer but I don't see how one could reasonably interpret a ground fact
> > as a "premise". So it seems to me the normative text and informative
> > EBNF are in agreement.
> >
> > Dave
> >
> > [1] http://www.w3.org/2005/rules/wg/track/issues/48
> > [2] Which I've not been able to validate from the record trail.
> > [3] That intention may be strange and hard to understand but that's the
> > nature of working group compromises :)
> >
> >
> >
> >
> > Sauf indication contraire ci-dessus:/ Unless stated otherwise above:
> > Compagnie IBM France
> > Siege Social : 17 avenue de l'Europe, 92275 Bois-Colombes Cedex
> > RCS Nanterre 552 118 465
> > Forme Sociale : S.A.S.
> > Capital Social : 611.451.766,20 €
> > SIREN/SIRET : 552 118 465 03644
> >
>



--
Jos de Bruijn
 Web:          http://www.debruijn.net/
 LinkedIn:     http://at.linkedin.com/in/josdebruijn
Received on Wednesday, 12 May 2010 12:18:07 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Wednesday, 12 May 2010 12:18:07 GMT