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RIF Negation

From: Adrian Paschke <adrian.paschke@gmx.de>
Date: Tue, 28 Apr 2009 13:52:56 +0200
To: "'Sandro Hawke'" <sandro@w3.org>
Cc: "'Christian De Sainte Marie'" <csma@fr.ibm.com>, <public-rif-wg@w3.org>
Message-ID: <007b01c9c7f7$df2f7a50$9d8e6ef0$@paschke@gmx.de>
Right, probably it makes sense to have explicit constructs for

Explicit/Strong/Classical negation                Neg
Default/Negation-as-failure/Weak/Inflationary     Not


-----Ursprüngliche Nachricht-----
Von: Sandro Hawke [mailto:sandro@w3.org] 
Gesendet: Dienstag, 28. April 2009 13:34
An: Adrian Paschke
Cc: 'Christian De Sainte Marie'; public-rif-wg@w3.org
Betreff: Re: AW: [Admin] Agenda for RIF telecon 28 April *ADDENDUM* 

> We discussed it in the last PRD telecon. The semantics of a generic
> "not" in case of PRD is clear since it used in a production rule set,
> i.e. it is inflationary not.

But is it also classical negation and NAF?  In particular, if I have
this ruleset:

   forall ?x
      if not ex:p(?x) then ex:q(?x)

this proposal defines that as a PRD ruleset.  To my eye, it could just
as easily be FOL or LPD.  As long as the semantics in all cases would be
the same, they could all use the same "not", but otherwise, it seems
like they need to use different operators.

> Alternative we could introduce many different constructs for
> negations, but this might be counterproductive to the interchange
> purpose of RIF. I would propose that the intended semantics of a rule
> set such as stratified, well-founded, stable models, is denoted by a
> special label (e.g. an attribute or additional construct) for the rule
> set and not by different constructs for negations. Otherwise a simple
> (business) rule set cannot be interchanged between a WFS rule engine
> and a Stable rule engine without a translation.

How would that work?  If a ruleset was labeled
"use-well-founded-semantics" and I was a "stable-semantics" engine, what
would I do with it?

     -- Sandro
Received on Tuesday, 28 April 2009 11:53:37 UTC

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