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[closed] Re: Restriction, DeprecatedClass in OWL Language Reference 31 March 2003

From: Jim Hendler <hendler@cs.umd.edu>
Date: Wed, 25 Jun 2003 20:17:32 -0400
Message-Id: <p05200f18bb1febe3980a@[10.0.0.229]>
To: "Richard H. McCullough" <rhm@cdepot.net>, "Guus Schreiber" <schreiber@swi.psy.uva.nl>
Cc: <public-webont-comments@w3.org>

At 9:11 AM -0700 6/25/03, Richard H. McCullough wrote:
>1. I consider your response satisfactory.

thanks Richard.  I'd like to suggest that you might repost the below 
to rdf-logic where it will get a wider readership and engender 
discussion.

>
>2. I would like to explain why
>     owl:Restriction  rdfs:subClassOf  rdfs:Property
>makes sense to me, based on the idea of a genus-differentia definition.
>a. In the weak sense (owl:equivalentClass), OWL has genus-differentia
>definitions.
>A species class is defined as the intersection of
>     a subClass of its genus class
>and one or more
>     Restriction class
>b. In the philosophical sense, a genus-differentia definition is a
>conjunction.
>A species class is defined as the conjunction of
>     ?x is an instance of its genus class
>and one or more
>     ?x  has subProperty
>where subProperty is related to a common Property of all the instances.
>It appears to me that the only purpose of owl:Restriction
>is to specify a subProperty of a class definition.
>
>Dick McCullough
>knowledge := man do identify od existent done;
>knowledge haspart proposition list;
>
>----- Original Message -----
>From: "Guus Schreiber" <schreiber@swi.psy.uva.nl>
>To: "Richard H. McCullough" <rhm@cdepot.net>
>Cc: <public-webont-comments@w3.org>
>Sent: Wednesday, June 25, 2003 3:24 AM
>Subject: Re: Restriction, DeprecatedClass in OWL Language Reference 31 March
>2003
>
>
>>  Richard H. McCullough wrote:
>>
>http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0090.html
>>
>>   > From: "Richard H. McCullough" <rhm@cdepot.net>
>>   > Subject: Re: Restriction, DeprecatedClass  in OWL Language Reference
>>  31 March 2003
>>   >
>>   >
>>   > So your class hierarchy is
>>   >
>>   >     rdfs:Class
>>   >         owl:Class
>>   >         owl:Restriction
>>   >         owl:DeprecatedClass
>>
>>
>>  Sorry if the previous message was not clear. The class hierarchy is (see
>>  Appendix B of Reference)
>>
>>  rdfs:Class
>>       owl:Class
>>           owl:Restriction
>>       owl:DeprecatedClass
>>
>>  So, owl:Restriction is a specific kind of owl:Class.
>>
>>   >
>>   > That raises several questions in my mind.
>>   > 1. Shouldn't you strive for
>>   >     owl:Class  owl:sameAs  rdfs:Class
>>
>>
>>  This is true in a weaker sense in OWL Full (owl:Class
>>  owl:equivalentClass rdfs:Class), but not in OWL DL. See the note in Sec.
>>  3.1 in the editor's draft of OWL Reference [1]:
>>
>>  [[
>>  NOTE: owl:Class is defined as a subclass of rdfs:Class. The rationale
>>  for having a separate OWL class construct lies in the restrictions on
>>  OWL DL (and thus also on OWL Lite), which imply that not all RDFS
>>  classes are legal OWL DL classes. In OWL Full these restrictions do not
>>  exist and therefore owl:Class and rdfs:Class are equivalent in OWL Full.
>>  ]]
>>
>>   > 2. Shouldn't owl:Restriction be a metaclass of rdf:Property?
>>   >     owl:Restriction  rdfs:subClassOf  rdf:Property
>>
>>
>>  owl:Restriction is not a property, it is a class of which the class
>>  extension is defined in terms of property constraints. See Sec. 3.1.2:
>>
>>  [[
>>  The class owl:Restriction is defined as a subclass of owl:Class. A
>>  restriction class should have exactly one triple linking the restriction
>>  to a particular property, using the  owl:onProperty property. The
>>  restriction class should also have exactly one triple that represents
>>  the value constraint c.q. cardinality constraint on the property under
>>  consideration, e.g., that the cardinality of the property is exactly 1.
>>  ]]
>>
>>   > 3. Likewise, shouldn't these be subClasses of rdf:Property
>>   >      owl:DataRange
>>
>>  This is not a property, but a class that can act as a datatype. See Sec.
>>  6.2:
>>
>>  [[
>>  In the case of an enumerated datatype, the domain value of owl:oneOf is
>>  a blank node of class owl:DataRange ....
>>  ]]
>>
>>   >      rdfs:Datatype
>>   >      rdfs:Literal
>>
>>  This is outside the scope of the OWL specifications. I would think this
>>  is not the case, however.
>>
>>   >      owl:DeprecatedProperty
>>
>>
>>  Correct, see Appendix B:
>>
>>  [[
>>  <rdfs:Class rdf:ID="DeprecatedProperty">
>>     <rdfs:label>DeprecatedProperty</rdfs:label>
>>     <rdfs:subClassOf rdf:resource="&rdf;Property"/>
>>  </rdfs:Class>
>>  ]]
>>
>>   > 4. It would be desirable to define an owl:Entity class,
>>   > disjoint from rdf:Property, which would include as subClasses
>>   >     owl:AllDifferent
>>   >     rdfs:Container
>>   >     owl:DeprecatedClass
>>   >     owl:Enumeration
>>   >     owl:Intersection
>>   >     rdf:List
>>   >     owl:Ontology
>>   >     owl:Union
>>   > 5. The above would produce the Class hierarchy
>>   >     owl:Thing
>>   >         owl:Entity
>>   >         rdf:Property
>>   >         rdf:Statement
>>   > where Entity,Property,Statement are disjoint and exhaustive.
>>   > This hierarchy is very meaningful, from both  metaphysical
>>   > and epistemological viewpoints.
>>   > Entity is the class of primary things that exist.
>>   > Property is the class of Entity properties plus meta properties
>>   >     (properties of things other than entities).
>>   > Statement is the class of relations between things.
>>
>>  The WG does not see the rationale for introducing owl:Entity at this
>>  time. I would suggest the discussion of this issue at the
>>  rdf-logic@w3.org discussion list.
>>
>>  Thanks again for your comments. Please let us know, cc-ing
>>  public-webont-comments@w3.org, whether this response is satisfactory.
>>
>>  Guus Schreiber
>>
>>  [1] http://www.daml.org/2002/06/webont/owl-ref-proposed
>>
>>   >
>>   > Dick McCullough
>>   > knowledge := man do identify od existent done;
>>   > knowledge haspart proposition list;
>>
>>  --
>>  Free University Amsterdam, Computer Science
>>  De Boelelaan 1081a, 1081 HV Amsterdam, The Netherlands
>>  Tel: +31 20 444 7739/7718
>>  E-mail: schreiber@cs.vu.nl
>>  Home page: http://www.cs.vu.nl/~guus/
>>
>>
>>
>>

-- 
Professor James Hendler				  hendler@cs.umd.edu
Director, Semantic Web and Agent Technologies	  301-405-2696
Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742	  *** 240-277-3388 (Cell)
http://www.cs.umd.edu/users/hendler      *** NOTE CHANGED CELL NUMBER ***
Received on Wednesday, 25 June 2003 20:17:43 GMT

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