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

From: Hans Teijgeler <hans.teijgeler@quicknet.nl>
Date: Sun, 5 Nov 2006 17:33:31 +0100
To: "'Leo Sauermann'" <leo.sauermann@dfki.de>
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: <000301c700f8$268ad2b0$6c7ba8c0@hans>
Hi Leo,
 
In your 1st link I read:
It may be natural to think of HYPERLINK
"http://www.w3.org/TR/2004/REC-rdf-primer-20040210/#reification"RDF
reification when representing n-ary relations. We do not want to use the RDF
reification vocabulary to represent n-ary relations in general for the
following reasons. The RDF reification vocabulary is designed to talk about
statements—individuals that are instances of rdf:Statement. A statement is a
object, predicate, subject triple and reification in RDF is used to put
additional information about this triple. This information may include the
source of the information in the triple, for example. In n-ary relations,
however, additional arguments in the relation do not usually characterize
the statement but rather provide additional information about the relation
instance itself. Thus, it is more natural to talk about instances of a
diagnosis relation or a purchase rather than about a statement. In the use
cases that we discussed in the note, the intent is to talk about instances
of a relation, not about statements about such instances.
 
In your 2nd link I read in chapter 4.3:
For one thing, it is important to note that in the conventional use of
reification, the subject of the reification triples is assumed to identify a
particular instance of a triple in a particular RDF document, rather than
some arbitrary triple having the same subject, predicate, and object. . . .
. . Thus, to fully support this convention, there needs to be some means of
associating the subject of the reification triples with an individual triple
in some document. However, RDF provides no way to do this.
 
This does not increase my enthousiasm for reification. 
 
Besides that I still see no sign that one can generalize this in an OWL
schema for validation purposes.
 
Regards,
Hans

   _____  

From: Leo Sauermann [mailto:leo.sauermann@dfki.de] 
Sent: Sunday, November 05, 2006 15:55
To: Hans Teijgeler
Cc: 'Paul Gearon'; 'SW-forum'; 'Chris Wilper'; Manola, Frank
Subject: Re: rdf:Property used as rdf:object in a triple


Hi Hans,

have you looked into Reification and did you try it out for your problem?

checkout reification, it will do what you need.
HYPERLINK
"http://www.w3.org/TR/swbp-n-aryRelations/#RDFReification"http://www.w3.org/
TR/swbp-n-aryRelations/#RDFReification
HYPERLINK
"http://www.w3.org/TR/2004/REC-rdf-primer-20040210/#reification"http://www.w
3.org/TR/2004/REC-rdf-primer-20040210/#reification

Or read this article, which explains why Reification may be what you may
need:
or if you should go for indivivduals
HYPERLINK
"http://www.w3.org/TR/swbp-n-aryRelations/"http://www.w3.org/TR/swbp-n-aryRe
lations/


greetings
Leo

Es begab sich aber da Hans Teijgeler zur rechten Zeit 05.11.2006 10:47
folgendes schrieb: 

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 [HYPERLINK "mailto:gearon@ieee.org"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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____________________________________________________

DI Leo Sauermann       HYPERLINK
"http://www.dfki.de/~sauermann"http://www.dfki.de/~sauermann 

DFKI GmbH

P.O. Box 2080          Fon:   +49 631 205-3503

67608 Kaiserslautern   Fax:   +49 631 205-3472

Germany                Mail:  HYPERLINK
"mailto:leo.sauermann@dfki.de"leo.sauermann@dfki.de

____________________________________________________


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Received on Sunday, 5 November 2006 16:34:18 GMT

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