- From: Rinke Hoekstra <hoekstra@uva.nl>
- Date: Fri, 28 Mar 2008 13:42:49 +0100
- To: Uli Sattler <sattler@cs.man.ac.uk>
- Cc: Alan Ruttenberg <alanruttenberg@gmail.com>, colombet@elet.polimi.it, "Web Ontology Language ((OWL)) Working Group WG" <public-owl-wg@w3.org>
Hi Uli, On 28 mrt 2008, at 13:32, Uli Sattler wrote: > >> 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 pfew... glad to hear that! >> 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... Ok, that really explains (Carsten's remark helped as well). >> 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? No, indeed. I was merely suggesting that if the Self restriction was allowed in special cases, that could be mentioned in the syntax doc. But as I now understand it, there is no such special case, rather some exception to the general rule, which has its own particular syntax. Thanks again for the explanation, -Rinke > > > 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 >> ----------------------------------------------- >> >> >> ----------------------------------------------- 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 12:43:29 UTC