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

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

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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 :)




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