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Re: limited negative guards for static OWL RL ruleset

From: Dave Reynolds <der@hplb.hpl.hp.com>
Date: Sat, 20 Dec 2008 15:32:50 +0000
Message-ID: <494D1022.5070800@hplb.hpl.hp.com>
To: Jos de Bruijn <debruijn@inf.unibz.it>
CC: RIF WG <public-rif-wg@w3.org>

Jos de Bruijn wrote:
> I was thinking a bit more about the problem of the negative guards and
> the static rule set we wish to provide for OWL RL.
> We established that without negative guards, we cannot provide a finite
> static ruleset, because the rules would depend on the literals actually
> being used in the ontology.
> 
> Now, a property of the OWL 2 language is that there is a strict
> separation between the object and data domains, both in the syntax and
> the semantics.  For example, it is not possible to assert that an IRI is
> a member of a datatype, nor is it possible to assert equality between
> and IRI and a concrete data value.
> Most importantly, the values of object properties can only be IRIs and
> the values of data properties can only be literals. And, in OWL 2 RL we
> only need to take individuals into account that are explicitly
> represented using IRI or literals.
> 
> Therefore, a statement like t[rdf:type -> DT], where DT is a datatype
> can never be derived if t is not a literal.  Consequently, we only need
> to do type checking of the form at the bottom of section 4.4.2 of [1]
> for literal values.
> 
> So, I believe that a restricted form kind of negative guard, namely one
> that is restricted to the domain of literals (e.g.,
> isNonIntegerLiteral), is sufficient for this static ruleset.

Agreed.

[I think when we discussed isNotType we mentioned the possibility of 
limiting it to isNotTypeLiteral.]

Dave
Received on Saturday, 20 December 2008 15:33:39 GMT

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