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[protege-discussion] OWL2 Classes

robert Stevens robert.stevens at manchester.ac.uk
Sun Mar 18 10:25:07 PDT 2012


SKOS concept is a class and the SKOS ontology is made in OWL2. Terms in a SKOS vocabulary are instances of this concept class. so, instead of making "universal" statements a about each and every member of a class as you would when adding a class restriction in OWL, one is just saying, when adding properties to instance, that this individual is related to that individual. One makes no claims about each and every instance of this class being related to at least one member of that class.

I don't know what you mean about adding properties being  problematic.
  ----- Original Message ----- 
  From: Jim Tivy 
  To: 'Robert Stevens' ; 'robert Stevens' ; 'User support for Core Protege and the Protege-Frames editor' 
  Sent: Sunday, March 18, 2012 4:54 PM
  Subject: RE: [protege-discussion] OWL2 Classes


  So you are saying SKOS Concept is not implemented as Class in OWL2?  If so, I agree.  Others have suggested that Concept becomes OWL2 class which I think is problematic since adding first class properties to OWL2 classes is not possible

   

  From: Robert Stevens [mailto:robert.stevens at manchester.ac.uk] 
  Sent: March-17-12 2:09 PM
  To: Jim Tivy; 'robert Stevens'; 'User support for Core Protege and the Protege-Frames editor'
  Subject: RE: [protege-discussion] OWL2 Classes

   

  Jim

  SKOS is OWL (2 or whatever  - the distinction at this point is immaterial).

  SKOS has one class called concept. All terms are indiviiduals of this class (though you can, of course, make your own subclasses of concept). it has built in object properties of broaderThan, narrowerthan, and relatedTo. It has built in annotation properties of  prefLable, altLabel, scopeNote and so on.

  SKOS is an OWL ontology and thus for all practical consideations OWL 2. it has access to all those featues should you want to use them. It just supplies the things that most thesaurae need. SKOS is an OWL (2) vocabulary designed to represent thesaurae.


  19:24 17/03/2012, Jim Tivy wrote:



  Robert
   
  Thanks for the tip - I will review OWL 1.
   
  I think OWL2 class is "Syntactic sugar" as they said in the OWL2 planning document.
   
  That said, the Class, Individual abstractions of OWL2 are very clean and coherent. The thing I am wrestling with is if a Class should have been an Individual.
   
  Jim
   
  From: robert Stevens [ mailto:robert.stevens at manchester.ac.uk] 
  Sent: March-17-12 11:33 AM
  To: Jim Tivy; 'robert Stevens'; 'User support for Core Protege and the Protege-Frames editor'
  Subject: Re: [protege-discussion] OWL2 Classes
   
  It is OWL and thus has what OWl has - it has domain and range constraints in the same way that OWL does.
   

  ----- Original Message ----- 

  From: Jim Tivy 

  To: 'robert Stevens' ; 'User support for Core Protege and the Protege-Frames editor' 

  Sent: Saturday, March 17, 2012 6:18 PM

  Subject: RE: [protege-discussion] OWL2 Classes

   

  Agreed SKOS has what I want but does SKOS have property domain and range definitions - something that approaches schema.

   

  I think OWL2 has a powerful data model that is coherent.  I find all the others to be somewhat less incoherent.

   

      <skos:Concept rdf:about=" http://my.site.com/#cleaning">

          <skos:prefLabel>Washing</skos:prefLabel>

          <skos:scopeNote>Washing results in something becoming physically cleaner.</skos:scopeNote>

          <skos:broader rdf:resource="http://my.site.com/#periodic%20maintenance"/>

          <skos:related rdf:resource="http://my.site.com/#problem%20solving"/>

          <skos:RT>cleaning maintenance</skos:RT>

          <skos:STA>Approved</skos:STA>

          <skos:INP>2011-11-15</skos:INP>

          <skos:APP>2011-11-15</skos:APP>

          <skos:UPD>2012-02-08</skos:UPD>

      </skos:Concept>

   

  From: protege-discussion-bounces at lists.stanford.edu [ mailto:protege-discussion-bounces at lists.stanford.edu] On Behalf Of robert Stevens

  Sent: March-17-12 2:11 AM

  To: User support for Core Protege and the Protege-Frames editor

  Subject: Re: [protege-discussion] OWL2 Classes

   

  it seems that you are describing SKOS - the W3C's Simple Knowledge Organisation System. SKOS itself is (sort of) a vocabulary in OWL2. SKOS has, without too much inspection, most of what you lay out below. There is an Editor plugin for Protege called SKOSED.

   

  SKOS has a class "concept" and individuals of that class are the vocabulary's terms. SKOS comes with  bt, nt, and rt properties, as well as notions of concept scheme and so on. You can also use all of OWL 2 within it (including the reasoning which is v interesting - at a trivial level, it wil put in all your inverses for you wihout you having to do it...)

   

  do say if it meets your needs - I'd be interested. 

  ----- Original Message ----- 

  From: Jim Tivy 

  To: 'User support for Core Protege and the Protege-Frames editor' 

  Sent: Saturday, March 17, 2012 1:07 AM

  Subject: Re: [protege-discussion] OWL2 Classes

   

  Hi Timothy

   

  Thanks for laying out the OWL2 formalisms.  I think OWL2 is a great data modelling system.  

  I only need to manipulate the data structure in a few ways and I am happy to write those by hand.  I would like to discuss data modelling first, then discuss reasoning (or rather agree not to discuss reasoning as right now reasoning does not seem interesting). 

   

  What I want to do is represent a Thesaurus which is a common well defined structure that is described many places including here: http://www.willpowerinfo.co.uk/thesprin.htm

   

  In English (not in OWL2) I think of it this way:

  There is a class of objects called Terms, some of which are in a hierarchy some of which are not.  Each Term needs to have the following properties:

  -        Scope Node

  -        Broad Term

  -        Narrow Term

  -        Related Terms

   

  My thought is to model this in OWL2 (excuse my paraphrase of OWL FL) as:

   

  Declare Class Term

  Declare Property(ScopeNode)

  Declare Property(HasChild)  // to subsume BroadTerm and NarrowTerm are 

  Declare Property(RelatedTerm)

  PropertyDomain(ScopeNode,Term)

  .

   

   

  Individual(myns:Dog)

  InClass(myns:Dog,Term)

  ObjectPropertyAssertion(myns:HasChild,myns:Boxer,myns:Dog)

   

  And so on.

   

  Is that enough information?

   

  Jim

   

   

   

   

   

   

  From: protege-discussion-bounces at lists.stanford.edu [ mailto:protege-discussion-bounces at lists.stanford.edu ] On Behalf Of Timothy Redmond

  Sent: March-16-12 5:13 PM

  To: protege-discussion at lists.stanford.edu

  Subject: Re: [protege-discussion] OWL2 Classes

   

  On 3/16/12 1:22 PM, Jim Tivy wrote: 

  Hi Folks

   

  I am looking to implement a Thesaurus using the OWL2 model.  It seems the recommended OWL2 modelling is to use a class for each term..  When I look at class, however, it seems that it is very weak because the mechanism for attaching properties to classes is weak.

  Actually I think that the OWL 2 formalism is very expressive.  The thing that you have to figure out is exactly what you mean by "attaching properties to a class".   So if you have a class, A, a class B and a property p you can say 

  all individuals in the class A must have a p-property value: 

A SubClassOf p someThing·  all individuals in the class A must have a p-property value that is in the class B: 

A SubClassOf p someB·  if some individual, i, has a p-property value then the individual i must be an element of the class A: 

p domain A 

   

  This is only just barely scratching the surface.  So tell us what you are trying to express and we can start thinking about whether OWL 2 can express it.

   

  I think I am better served to have one class called "Terms" or "Concepts" whose individuals express the Thesaurus.  In that way I can constrain properties and reason about these individuals more naturally.

   

  It may be that this is true but it seems very unlikely to me.  My sense is that if you don't have a rich class structure then you are not going to have much to reason about with the individuals.

   

  I realize Class==Concept in OWL2, however I think that since Class itself is not an individual that it is too weak.  What ever happened to the notion of the Class Class.

  What is the "Class Class"?  If you are thinking of meta-modeling, then my reaction is that I think that realistic meta-modeling is probably often quite difficult to get right.  But in any case, the starting point is to figure out what you are trying to say.  Then we can figure out what language capabilities you need to express your concept.

  -Timothy

   

  Jim

   

  Jim Tivy - CTO, Bluestream

  Skype: jimt.vanc

   

   

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