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Re: Representing anonymous individual in SemWeb Best Practice documents

From: Alan Rector <rector@cs.man.ac.uk>
Date: Sat, 27 Oct 2007 11:24:03 +0100
Message-Id: <A4A3D935-2D48-427C-8807-68ECA3DFEA0D@cs.man.ac.uk>
Cc: <public-swbp-wg@w3.org>
To: Benedicto Rodriguez <br205r@ecs.soton.ac.uk>

Bene

Apologies.  The N3 syntax may not have been checked as carefully as  
it should be.
Most of us who wrote it now use the Manchester Simplified Syntax  
supported by
Protege4Alpha (It is much more than an Alpha really) which you can  
download from
the usual protege.stanford.edu.

It exports just about everything except N3, which most of us don't  
use currently for OWL.

In that syntax:

	Person THAT has_health_status SOME Good_health_status

certainly works.  	and you can make an individual
	
	John

of type

	has_health_status SOME Good_health_status

Note that you don't make a Fact about John but make John of type the  
anonymous class.

(NB as a typographical convention we usually put the keywords in  
upper case in emails and the like.  They are in lower case but  
highlighted in colour in the tool).

The analogous expression works for the classes as value case.

	Book THAT dc_subject SOME Lion

(nb: we usually keep "dc:subject" itself as an annotation rather than  
using it directly, to avoid various technical conflicts between the  
rdf and OWL DL.

Hope this helps.

Regards

Alan





On 17 Oct 2007, at 01:23, Benedicto Rodriguez wrote:

>
>
> -----Original Message-----
> From: Benedicto Rodriguez
> Sent: 15 October 2007 00:54
> To: 'public-owl-dev@w3.org'
> Subject: Representing anonymous individual in SemWeb Best Practice
> documents
>
>
> Hello everyone,
>
> [...]
>
> Two of the documents in the SWBPD WG ([1], [2]) talk about  
> representing
> anonymous individuals as the value of a property using an existential
> restriction.
>
> [1] Representing Classes As Property Values on the Semantic Web. (See:
> Approach 4). http://www.w3.org/TR/swbp-classes-as-values/
>
> [2] Representing Specified Values in OWL: "value partitions" and  
> "value
> sets". (See: Pattern 2, variant 2).
> http://www.w3.org/TR/swbp-specified-values/
>
> In both cases only the N3 syntax for this variant is provided, not the
> corresponding OWL implementation.
> According to both documents the resulting OWL implementation is within
> OWL-DL expressivity.
>
> *** My goal is simply to write this OWL implementation within OWL- 
> DL but
> I run into some problems doing so.
>
> A) 	I noticed that the N3 syntax provided in [1] and [2] for this
> variant doesn't parse in the only N3 validator online I found
> (http://rdfabout.com/demo/validator/ listed in the SemanticWebTools  
> page
> of the ESW Wiki).
>
> Now, I'm not sure if this is because the N3 syntax is actually NOT
> correct or because of an issue with the parser. (?)
>
> In [2] for example. To parse this variant I used the file
> http://www.w3.org/TR/swbp-specified-values/value-partitions- 
> variant-1.n3
> (provided in [2]) replacing the definition of :John in the file for  
> the
> definition shown below (also provided in [2]) and after a couple of
> tweaks to bypass an empty relative URI issue:
>
> ### Define John as an individual of type person and of type
> has_health_status someValuesFrom Good_health_status
> :John
>     a      :Person ;
>     [    a      owl:Restriction;
>          owl:onProperty :has_health_status ;
>          owl:someValuesFrom :Good_health_value
>     ].
>
> B) 	The following modification to the previous N3 snippet solved the
> parsing problem, but I'm not sure if this is what the original N3
> expression shown in A) intended to represent (?):
>
> :John
>     a      :Person ;
>     :has_health_value
>         [    a      owl:Restriction;
>              owl:onProperty :has_health_status ;
>              owl:someValuesFrom :Good_health_value
>         ].
>
> Now, I have tried 2 options when converting the N3 snippet shown in A)
> into OWL.
> (Again, the original claim in [1] and [2] is the representation of an
> anonymous individuals as the value of a property using an existential
> restriction).
>
> C) 	Option 1: This OWL implementation would place the model is in
> OWL Full because the value of the property "has_health_status" is an
> anonymous class defined by a restriction rather than an anonymous
> individual.
> This deviates from the intention in [1] and [2].
>
> <Person rdf:about="#John">
>    <has_health_status>
>       <owl:Restriction>
>  	   <owl:someValuesFrom>
>             <owl:Class rdf:about="#Good_health_value"/>
>          </owl:someValuesFrom>
>          <owl:onProperty>
>             <owl:FunctionalProperty rdf:about="#has_health_status"/>
>          </owl:onProperty>
>       </owl:Restriction>
>    </has_health_status>
> </Person>
>
> D) 	Option 2: This OWL implementation leaves the model in OWL-DL
> because the value of the property "has_health_status" is an anonymous
> individual from the class "Good_health_value".
> However it doesn't seem to correspond to the original N3 expression
> given that it lacks the "someValuesFrom" restriction.
>
>   <Person rdf:about="#John">
> 	  <has_health_status>
> 		<Good_health_value/>		
> 	  </has_health_status>
>   </Person>
>
> E) 	The same issues and same possible solutions apply to the
> representation of :LionsLifeInThePrideBook in Approach 4 in document
> [1]:
>
> :LionsLifeInThePrideBook
>       a       :Book;
>       [ a       owl:Restriction ;
>                 owl:onProperty dc:subject ;
>                 owl:someValuesFrom :Lion      ];
>       rdfs:seeAlso <http://isbn.nu/0736809643> ;
>       :bookTitle "Lions: Life in the Pride" .
>
> In conlusion, any suggestions of what the OWL-DL implementation of the
> N3 snippet in A) should be?
> Is the OWL in D) a sensible solution?
>
> Additionally, any comments regarding what may be causing the parsing
> issue of the N3 shown in A)?
> Do you think the modification shown in B) (that parses OK), is what  
> [2]
> intended to represent?
>
> Any other comments/feedback would be very welcome and appreciated.
>
> Regards,
> Bene Rodriguez
>
> Postgraduate Student | Intelligence, Agents and Multimedia Group |
> School of Electronics and Computer Science | University of  
> Southampton |
> Southampton SO17 1BJ | United Kingdom | Phone: +44 23 8059 3122 |  
> Email:
> bene@soton.ac.uk
>

-----------------------
Alan Rector
Professor of Medical Informatics
School of Computer Science
University of Manchester
Manchester M13 9PL, UK
TEL +44 (0) 161 275 6149/6188
FAX +44 (0) 161 275 6204
www.cs.man.ac.uk/mig
www.clinical-esciences.org
www.co-ode.org
Received on Saturday, 27 October 2007 20:23:15 UTC

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