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Re: rdf:Property used as rdf:object in a triple

From: David Price <david.price@eurostep.com>
Date: Sun, 5 Nov 2006 13:20:35 +0000
To: "Hans Teijgeler" <hans.teijgeler@quicknet.nl>
Cc: "'Paul Gearon'" <gearon@ieee.org>, "'SW-forum'" <semantic-web@w3.org>, "'Chris Wilper'" <cwilper@cs.cornell.edu>, "Manola, Frank" <fmanola@acm.org>
Message-Id: <200611051320.36225.david.price@eurostep.com>

Hans,

It's my understanding that even OWL Full doesn't natively handle all of these 
examples, and therefore the Best Practices approaches for simulating N-ary 
relationships[1] was developed. For example, (N weldedTo M) inspectedBy John 
may need to be represented by an instance W of a class WeldInspection with 
properties W weldEnd1 N, W weldEnd2 M and W inspectedBy john.

It would be interesting to hear from the core OWL experts about when dropping 
out of OWL Full into these Best Practices is necessary and what the 
consequences might be. 

Cheers,
David

[1] http://www.w3.org/TR/swbp-n-aryRelations/

On Sunday 05 November 2006 09:47, Hans Teijgeler wrote:
> Hi Paul,
>
> Thanks for your response! (and thanks as well to Chris and Frank).
>
> Let me explain this with a simple example:
>
> *
>
> 	John isInvolvedWith Jane
> *
>
> 	Jane's father Pete givesApprovalTo that relationship
>
> This means that the isInvolvedWith relationship is the rdf:object of the
> predicate 'givesApprovalTo'.
>
> We then also want to represent the owl:Restriction that Fathers approve
> such relationships of their daughters (granted, it's a bit old-fashioned,
> but it's just an example).
>
> This example is not rare. Another one is:
>
> *
>
> 	Nozzle N1 isWeldedTo Vessel V1
> *
>
> 	that welded connection isInspectedBy John
>
> I guess that I should start using reification, but quite honestly I am too
> dumb to understand the text in [1]
> [1] HYPERLINK
> "http://www.w3.org/TR/rdf-mt/#Reif"http://www.w3.org/TR/rdf-mt/#Reif
>
> Is reification at all possible in an OWL environment? It seems not to be
> the case.
>
> Mind you, we define "templates" with Restrictions in OWL that will be used
> to validate the zillions of instances of those templates in RDF. So for
> example we define, using 15926 model lingo, a template for DirectConnection
> of two PossibleIndividuals, and make sure, using owl:Restrictions, that any
> instance of that template has an instance of PossibleIndividual at both
> sides. These templates can be specialized by onProperty restrictions to,
> for example, a template for welded connections that can only be between
> instances of PossibleIndividual that can be welded at all.
>
> I hope I haven't made this too complex :-)
>
> Regards,
> Hans
>
> ____________________
> OntoConsult
> Hans Teijgeler
> ISO 15926 specialist
> Netherlands
> +31-72-509 2005
> HYPERLINK "http://www.infowebml.ws/"www.InfowebML.ws
> HYPERLINK "mailto:hans.teijgeler@quicknet.nl"hans.teijgeler@quicknet.nl
>
>
>    _____
>
> From: Paul Gearon [mailto:gearon@ieee.org]
> Sent: Saturday, November 04, 2006 23:56
> To: Hans Teijgeler
> Cc: SW-forum
> Subject: Re: rdf:Property used as rdf:object in a triple
>
>
>
> On Nov 4, 2006, at 6:25 AM, Hans Teijgeler wrote:
>
>
> Folks,
>
> rdf:Property is a subClassOf rdfs:Resource, so syntactically a property
> could be the rdf:object of a triple.
>
> My question is, whether or not there is something against doing that from a
> semantics/reasoning point of view.
>
> Can anybody shed some light on this?
>
>
> There's certainly no rule against it.  Reification requires it.  So does
> rdfs:subPropertyOf.
>
> As for semantics... you can get away with a lot in RDF.  But if you want to
> keep things as valid OWL-Lite or OWL-DL then you have to be more careful,
> as properties are treated a little differently to other resources. 
> Properties only start getting back the "privileges" of other types of
> resources (like classes) when you get up to OWL-Full.
>
> Paul
>
>
> --
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Received on Sunday, 5 November 2006 13:21:45 GMT

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