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Re: Negation and Disjunction in RIF

From: Axel Polleres <axel.polleres@deri.org>
Date: Tue, 04 Dec 2007 16:14:04 +0000
Message-ID: <47557CCC.3000208@deri.org>
To: Pathak.Jyotishman@mayo.edu
CC: public-rif-comments@w3.org, "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>

Dear Jyoti,

Sorry for the late reply, first of all....

> Hello everyone,
> 
> I am a newcomer to this field and trying to learn. The question I
> have is w.r.t. support for negation (specifically NAF: negation as
> failure) and disjunction in RIF. As far as I know, SWRL natively does
> not support them. Is this true for RIF as well?
> 
> Thank you, - Jyoti


Indeed, RIF's Basic Logic dialect (BLD) [1] does not support negation as
failure (NAF). Extensions of rule lanaugages by NAF and other variations
of negation (see [2]) are beyond phase 1 of RIF. The working group
however does at this point not preclude that we will already be starting
to work on dialects which include such extensions in parallel with
finishing Phase 1.

For instance, in the current proposal for a production rule dialect
(PRD), see [3], you will find a construct for negation as failure, which
is currently under discussion, i.e. this draft is not to be considered
as finalized.

Similar considerations apply for disjunction. Note that BLD allows
disjunction in rule bodies, but not in rule heads. Again, later dialects
and the generic extensibility mechanism we are currently working on
shall allow for such extensions.

As for SWRL, note that SWRL is an *extension* of OWL, thus, before
addressing SWRL completely, we need to address OWL compatibility [4] in
more detail, which is also work in progress at the moment.


with best regards,
Axel

1. http://www.w3.org/TR/2007/WD-rif-bld-20071030
2. http://www.w3.org/2005/rules/wg/wiki/negation
3. http://www.w3.org/2005/rules/wg/wiki/PRdialect
4. http://www.w3.org/TR/2007/WD-rif-rdf-owl-20071030/




-- 
Dr. Axel Polleres
email: axel@polleres.net  url: http://www.polleres.net/
Received on Tuesday, 4 December 2007 16:14:35 GMT

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