- From: Jim Hendler <hendler@cs.umd.edu>
- Date: Wed, 25 Jun 2003 20:17:32 -0400
- 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 UTC