Christoph; An addendum to Irene's post. One can probably work really
hard to close the world and make the right reasoning in Pellet, etc.
An alternative is to use simple SPARQL queries to make the inferences:
CONSTRUCT {?x a :ValidCert .}
WHERE {?x a :Certificate .
OPTIONAL {?x :hasValidity ?certValue .}
FILTER (!bound(?certValue)) .}
CONSTRUCT {?x a :ValidCert .}
WHERE {?x a :Certificate .
?x :hasValidity :valid .}
The first CONSTRUCT clause finds all instances of Certificate that do
not have a "hasValidity" property. The second finds all instances
that have the value "valid" for the "hasValidity" property.
This alternative has the advantage of allowing one to specify directly
the inferences that are necessary for the application - and there are
no OWA's to interfere with reasonable reasoning.
SPARQLMotion can be used to create scripts that run a number of these
queries, effectively allowing one to tailor a limited inference engine
to meet requirements. SPIN can help automate when and where such
queries are applied - SPIN rules attached to a class can be designed
to compute class membership. SPIN constraints can be designed to
check for data consistency problems. Etc.
-- Scott
On Dec 30 2008, 6:41 pm, "Irene Polikoff" <[email protected]>
wrote:
> Yes, you are right. Open world assumption does not make this conclusion
> possible for the standard OWL inferencing. However, with the beta release of
> 3.0 scheduled for tomorrow, you will be able to use
> SPINhttp://www.topquadrant.com/topbraid/composer/spin.htmlto implement this
> inferencing.
>
> Regards,
>
> Irene Polikoff
> Executive Partner, TopQuadrant
> tel: 914-777-0888/ cell: 914-329-8576www.topquadrant.com
>
> -----Original Message-----
> From: [email protected]
>
> [mailto:[email protected]] On Behalf Of Christoph
> Sent: Tuesday, December 30, 2008 12:22 PM
> To: TopBraid Composer Users
> Subject: [tbc-users] open world assumption problem
>
> I would like to have a class "Certificate" and two other Classes "Valid
> Certificates" and "Invalid Certificates". Authorities can set a certificate
> to be an invalid one. How can I reason all valid certificates (all
> certificates that are not invalid ones)? Is this possible? This might be an
> open world assumption problem. If a certificate is not explicitly set
> "invalid", the reasoner cannot know if it is therefore valid. It might be
> the case or not.
>
> Thanks!
>
>
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