W3C home > Mailing lists > Public > public-webont-comments@w3.org > June 2003

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

From: Richard H. McCullough <rhm@cdepot.net>
Date: Wed, 25 Jun 2003 09:11:56 -0700
Message-ID: <008001c33b34$abb686b0$bd7ba8c0@rhm8200>
To: "Guus Schreiber" <schreiber@swi.psy.uva.nl>
Cc: <public-webont-comments@w3.org>

1. I consider your response satisfactory.

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/
>
>
>
>
Received on Wednesday, 25 June 2003 12:13:10 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:43:29 GMT