- From: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>
- Date: Sat, 27 Jun 2009 23:11:48 +0100
- To: Michael Schneider <schneid@fzi.de>
- Cc: "OWL 1.1" <public-owl-wg@w3.org>, Boris Motik <boris.motik@comlab.ox.ac.uk>
I think that the confusion arises from the fact that the forest in question is not defined by the ontology assertions. The point is that in order for the ontology to be in OWL 2 DL it must be possible to arrange the anonymous individuals in a forest such that the three conditions (which *do* refer to ontology assertions) are satisfied. In the case of the second example, it is easy to see that there can be no such forest satisfying both the first and second conditions, namely: "for each assertion in Ax of the form ObjectPropertyAssertion( OPE _:x _:y ), either _:x is a child of _:y or _:y is a child of _:x in F" and "for each pair of anonymous individuals _:x and _:y such that _:y is a child of _:x in F, the set Ax contains at most one assertion of the form ObjectPropertyAssertion( OPE _:x _:y ) or ObjectPropertyAssertion ( OPE _:y _:x )". In fact the purpose of adding the second example was to emphasise that not only cycles, but any non-tree like arrangement of anonymous individuals is illegal in OWL 2 DL. Regards, Ian On 27 Jun 2009, at 01:01, Boris Motik wrote: > Hello, > > No, not really: since OWL 2 has inverse roles, the actual > directionality of the > property assertions doesn't matter. That is, the role assertion > > ObjectPropertyAssertion( a:hasDaughter _:b1 _:b2 ) > > is equivalent to > > ObjectPropertyAssertion( InverseObjectProperty(a:hasDaughter) _:b2 > _:b1 ) > > Now if the latter is circular, the former should be circular as > well, given that > the two assertions are semantically equivalent. > > Regards, > > Boris > >> -----Original Message----- >> From: Michael Schneider [mailto:schneid@fzi.de] >> Sent: 27 June 2009 01:52 >> To: Boris Motik >> Cc: OWL 1.1 >> Subject: RE: question on "forest-like anonymous individuals" >> restriction of >> OWL 2 DL >> >> Hi Boris! >> >> The second counter example states >> >> ObjectPropertyAssertion( a:hasChild _:b1 _:b2 ) >> ObjectPropertyAssertion( a:hasDaughter _:b1 _:b2 ) >> >> But shouldn't it be >> >> ObjectPropertyAssertion( a:hasChild _:b1 _:b2 ) >> ObjectPropertyAssertion( a:hasDaughter _:b2 _:b1 ) >> ^^^^^^^^^ >> >> in order to build a circular structure? >> >> Cheers, >> Michael >> >>> -----Original Message----- >>> From: Boris Motik [mailto:boris.motik@comlab.ox.ac.uk] >>> Sent: Friday, June 26, 2009 1:29 PM >>> To: Michael Schneider; 'OWL 1.1' >>> Subject: RE: question on "forest-like anonymous individuals" >>> restriction >>> of OWL 2 DL >>> >>> Hello, >>> >>> In response to Michael's comment, Ian and I have made the following >>> changes to >>> the Syntax document: >>> >>> http://www.w3.org/2007/OWL/wiki/index.php? >>> title=Syntax&diff=24654&oldid= >>> 24647 >>> >>> I hope things are clearer now. Please let me know should you have >>> any >>> comments. >>> >>> Regards, >>> >>> Boris >>> >>>> -----Original Message----- >>>> From: public-owl-wg-request@w3.org [mailto:public-owl-wg- >>> request@w3.org] On >>>> Behalf Of Michael Schneider >>>> Sent: 29 May 2009 20:46 >>>> To: OWL 1.1 >>>> Subject: question on "forest-like anonymous individuals" >>>> restriction >>> of OWL 2 >>>> DL >>>> >>>> Hi all! >>>> >>>> I had to explain to someone the "forest-like anonymous individuals" >>>> restriction of OWL 2 DL (Section 11.2 of the Structural Spec), >>>> but I >>> found >>>> myself uncertain about it. In particular, I'm unclear how >>>> "fixed" the >>> variable >>>> "OPE" is in the set of conditions. >>>> >>>> But it's easier to show my problem by an example: It's clear to me >>> (also from >>>> the example following the formal definition) that the following is >>> /not/ >>>> allowed in OWL 2 DL: >>>> >>>> _:x :p _:y >>>> _:y :p _:x >>>> >>>> But what about >>>> >>>> _:x :p _:y >>>> _:y :q _:x >>>> >>>> with /different/ properties? >>>> >>>> Michael >>>> >>>> -- >>>> Dipl.-Inform. Michael Schneider >>>> Research Scientist, Dept. Information Process Engineering (IPE) >>>> Tel : +49-721-9654-726 >>>> Fax : +49-721-9654-727 >>>> Email: michael.schneider@fzi.de >>>> WWW : http://www.fzi.de/michael.schneider >>>> >>> ==================================================================== >>> === >>>> FZI Forschungszentrum Informatik an der Universität Karlsruhe >>>> Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe >>>> Tel.: +49-721-9654-0, Fax: +49-721-9654-959 >>>> Stiftung des bürgerlichen Rechts, Az 14-0563.1, RP Karlsruhe >>>> Vorstand: Prof. Dr.-Ing. Rüdiger Dillmann, Dipl. Wi.-Ing. Michael >>> Flor, >>>> Prof. Dr. Dr. h.c. Wolffried Stucky, Prof. Dr. Rudi Studer >>>> Vorsitzender des Kuratoriums: Ministerialdirigent Günther >>>> Leßnerkraus >>>> >>> ==================================================================== >>> === >>>> >>> >> >> -- >> Dipl.-Inform. Michael Schneider >> Research Scientist, Dept. Information Process Engineering (IPE) >> Tel : +49-721-9654-726 >> Fax : +49-721-9654-727 >> Email: michael.schneider@fzi.de >> WWW : http://www.fzi.de/michael.schneider >> ===================================================================== >> == >> FZI Forschungszentrum Informatik an der Universität Karlsruhe >> Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe >> Tel.: +49-721-9654-0, Fax: +49-721-9654-959 >> Stiftung des bürgerlichen Rechts, Az 14-0563.1, RP Karlsruhe >> Vorstand: Prof. Dr.-Ing. Rüdiger Dillmann, Dipl. Wi.-Ing. Michael >> Flor, >> Prof. Dr. Dr. h.c. Wolffried Stucky, Prof. Dr. Rudi Studer >> Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus >> ===================================================================== >> == > > >
Received on Saturday, 27 June 2009 22:12:33 UTC