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

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

From: Jos de Bruijn <jos.debruijn@gmail.com>
Date: Wed, 12 May 2010 12:19:15 +0200
Message-ID: <4BEA80A3.2070103@gmail.com>
To: Dave Reynolds <dave.e.reynolds@googlemail.com>
CC: Axel Polleres <axel.polleres@deri.org>, Christian De Sainte Marie <csma@fr.ibm.com>, RIF <public-rif-wg@w3.org>

On 05/12/2010 12:09 PM, Dave Reynolds wrote:
> 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.

Then I find it strange that PRD allows asserting class membership facts.

> 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". 

I agree that a ground fact could not be interpreted as a premise.
However, it is unclear in the phrasing whether the last part of the
sentence applies to all formulas or only to rules (whatever they may be).

Best, Jos

> 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 :)

Jos de Bruijn
  Web:          http://www.debruijn.net/
  LinkedIn:     http://at.linkedin.com/in/josdebruijn
Received on Wednesday, 12 May 2010 10:19:52 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 21:47:58 UTC