- From: Uli Sattler <sattler@cs.man.ac.uk>
- Date: Fri, 28 Mar 2008 12:32:23 +0000
- To: Rinke Hoekstra <hoekstra@uva.nl>
- Cc: Alan Ruttenberg <alanruttenberg@gmail.com>, colombet@elet.polimi.it, "Web Ontology Language ((OWL)) Working Group WG" <public-owl-wg@w3.org>
On 28 Mar 2008, at 08:17, Rinke Hoekstra wrote: > Hi Uli, > > Hm. Your answer got me a bit confused.. Like Marco, I thought > ObjectExistsSelf was not allowed on composed properties at all. ...and you thought correctly > Are you saying they *are* allowed on any class, or just owl:Thing? > no - all I am saying is that ObjectPropertyReflexive(P) is allowed on a composite property, despite the fact that this is equivalent to SubClassOf(owl:thing, ObjectExistsSelf(P)) -- but this equivalence doesn't mean that (a) an ontology will contain the latter axiom or (b) a reasoner will have to be able to handle such axioms, or in general ObjectExistsSelf(.) on composite properties... This equivalence only shows that ObjectPropertyReflexive(P) *can* be viewed as a *special* of an axiom involving a ObjectExistsSelf(.) on a composite property... > If so, I guess the description in the syntax document could use some > clarification. ...do you think so? I would think that adding a note "yes indeed, this is not a type/oversight" is perhaps useful, but I am not sure we really want this explanation in there? Cheers, Uli > > > -Rinke > > > On 27 mrt 2008, at 20:24, Uli Sattler wrote: >> >> On 27 Mar 2008, at 18:27, Alan Ruttenberg wrote: >> >>> >>> >>> Begin forwarded message: >>> >>>> Resent-From: public-owl-dev@w3.org >>>> From: "Marco Colombetti" <colombet@elet.polimi.it> >>>> Date: March 26, 2008 12:11:47 PM EDT >>>> To: <public-owl-dev@w3.org> >>>> Subject: Nonstructural restrictions >>>> Archived-At: <http://www.w3.org/mid/002e01c88f5c$18ecbb70$7c46fea9@lapcolombetti >>>> > >>>> >>>> Hi. >>>> >>>> In http://www.webont.org/owl/1.1/owl_specification.html “OWL 1.1 >>>> Web Ontology Language - Structural Specification and Functional- >>>> Style Syntax - Editor's Draft of 23 May 2007”. >>>> >>>> in Section 7 “Nonstructural Restrictions on Axioms”, >>>> >>>> I find that: >>>> • Only simple object properties are allowed to occur in Ax in >>>> • ObjectMinCardinality, ObjectMaxCardinality, >>>> ObjectExactCardinality, and ObjectExistsSelf classes, and >>>> • ObjectPropertyFunctional, >>>> InverseFunctionalObjectProperty,ObjectPropertyIrreflexive, >>>> ObjectPropertyAsymetric, andDisjointObjectProperty axioms. >>>> I wonder whether composite properties should also be forbidden in >>>> ObjectPropertyReflexiveaxioms, given that these are equivalent >>>> toSubObjectPropertyOf(owl:Thing,ObjectExistsSelf(P)). >>>> >> >> good question: ObjectPropertyReflexive(P) for a non-simple/ >> composite property is ok. This might be a bit hard to see, but i >> will try to explain. It is equivalent, as you say, to >> >> SubClassOf(owl:thing, ObjectExistsSelf(P)), >> >> but this is also ok: in principal, what is difficult for a >> composite property, is >> >> SubClassOf(AClass, ObjectAllValuesFrom(P AnotherClass)), >> >> Ie, universal/all restrictions are difficult for them, but not >> existential/some restrictions as in "ObjectExistSelf".... >> >> Cheers, Uli >> >> >>>> Regards, >>>> >>>> Marco Colombetti >>>> >>>> >>> >> > > ----------------------------------------------- > Drs. Rinke Hoekstra > > Email: hoekstra@uva.nl Skype: rinkehoekstra > Phone: +31-20-5253499 Fax: +31-20-5253495 > Web: http://www.leibnizcenter.org/users/rinke > > Leibniz Center for Law, Faculty of Law > University of Amsterdam, PO Box 1030 > 1000 BA Amsterdam, The Netherlands > ----------------------------------------------- > > >
Received on Friday, 28 March 2008 12:30:39 UTC