- From: Rinke Hoekstra <hoekstra@uva.nl>
- Date: Wed, 17 Sep 2008 17:58:41 +0200
- To: "Boris Motik" <boris.motik@comlab.ox.ac.uk>
- Cc: "'OWL 2'" <public-owl-wg@w3.org>
Excellent, thanks! -Rinke On 17 sep 2008, at 17:49, Boris Motik wrote: > Hello, > > The word "possibly" denoted the fact that you could have either the > simple inclusions, or, if you wanted, you could have property > chains. I agree that this was ambiguous, so I just changed it to > "object property inclusion (<span > class="nonterminal">SubObjectPropertyOf</span>) with or without > property chains". I hope things are clear now. > > Boris > >> -----Original Message----- >> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org >> ] On Behalf Of Rinke Hoekstra >> Sent: 17 September 2008 16:44 >> To: Boris Motik >> Cc: 'OWL 2' >> Subject: Re: Top property in property chains for the EL fragment. >> >> >> Hi Boris, >> >> On 17 sep 2008, at 17:21, Boris Motik wrote: >>> Yes, this is intentional. The goal in the design of all the profiles >>> of OWL 2 was to make them syntactic fragments of OWL 2 DL; >>> otherwise, the entire language hierarchy becomes quite messy. As a >>> consequence, the restrictions on not using owl:TopObjectProperty >>> in EL++ is "unnecessarily"; however, hardly seems like a reason for >>> concern. >> >> Ok thanks (it got me a bit confused). >> >> Along the same lines, this means that property chains are allowed in >> SubObjectProperty statements, as there are no syntactic restrictions >> that disallows them. Perhaps the 'possibly' should then be removed in >> [3] to make the line less ambiguous. >> >> Best, >> >> Rinke >> >>> >>> >>> Regards, >>> >>> Boris >>> >>>> -----Original Message----- >>>> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org >>>> ] On Behalf Of Rinke Hoekstra >>>> Sent: 17 September 2008 16:10 >>>> To: OWL 2 >>>> Subject: Top property in property chains for the EL fragment. >>>> >>>> >>>> Hi, >>>> >>>> After reading Uli's response to a question from Jeff Thompson >>>> (below), >>>> I just checked the global restrictions section for the EL profile >>>> in >>>> [1]. It doesn't mention the fact that the top-property is allowed >>>> in >>>> role chains in the EL fragment (but not in DL itself [2]). Is this >>>> intentional? >>>> >>>> The EL feature overview states "possibly involving property chains" >>>> for SubObjectProperty [3]... does this mean we don't know whether >>>> property chains can be used in EL? Or that using property chains is >>>> allowed? >>>> >>>> -Rinke >>>> >>>> [1] http://www.w3.org/2007/OWL/wiki/Profiles#Global_Restrictions >>>> [2] http://www.w3.org/2007/OWL/wiki/Syntax#Global_Restrictions_on_Axioms >>>> [3] http://www.w3.org/2007/OWL/wiki/Profiles#Feature_Overview >>>> >>>> >>>> Begin forwarded message: >>>> >>>>> Resent-From: public-owl-dev@w3.org >>>>> From: Uli Sattler <sattler@cs.man.ac.uk> >>>>> Date: 29 augustus 2008 11:33:31 GMT+02:00 >>>>> To: Jeff Thompson <jeff@thefirst.org> >>>>> Cc: public-owl-dev@w3.org >>>>> Subject: Re: owl:TopObjectProperty in property chains? >>>>> >>>>> >>>>> >>>>> On 28 Aug 2008, at 08:52, Jeff Thompson wrote: >>>>> >>>>>> >>>>>> Thanks for the references! These are right on target. I will >>>>>> study them. >>>>>> In "Tractable Rules for OWL 2", top of page 6, there is the >>>>>> example >>>>>> to translate: >>>>>> >>>>>> NutAllergic(x) ? NutProduct(y) ? dislikes(x, y) >>>>>> >>>>>> to >>>>>> >>>>>> NutAllergic ? ?RNutAllergic.Self >>>>>> NutProduct ? ?RNutProduct.Self >>>>>> RNutAllergic ? U ? RNutProduct ? dislikes >>>>>> >>>>>> I'm temporarily gratified that this has the use of the universal >>>>>> role >>>>>> in a role chain, similar to my original example (hence the name >>>>>> of >>>>>> this >>>>>> thread). But as I study the paper, I suspect it will say that >>>>>> this >>>>>> example is not a tractable rule for OWL 2 (despite the title of >>>>>> the >>>>>> paper). >>>>>> >>>>> >>>>> Hi Jeff, I didn't mention this example/way of approximating >>>>> roles in >>>>> my previous emails because they require, additionally, some >>>>> lengthy >>>>> explanation about when you can and can't use them without >>>>> violating >>>>> the 'regularity' condition i mentioned......this regularity >>>>> condition ensures decidability of reasoning and that our reasoning >>>>> techniques work. >>>>> >>>>> The thing is that, in OWL2 DL, you cannot use >>>>> owl:TopObjectProperty >>>>> in subproperty chains -- you could do so in EL++, a DL described >>>>> in >>>>> >>>>> http://www.webont.org/owled/2008dc/papers/owled2008dc_paper_3.pdf >>>>> Pushing the EL Envelope Further. Franz Baader, Sebastian Brandt, >>>>> and Carsten Lutz. In Proc. of the Washington DC workshop on OWL: >>>>> Experiences and Directions (OWLED08DC), 2008. >>>>> >>>>> If you want to know more about this, let me know. >>>>> >>>>> Cheers, Uli >>>>> >>>>> >>>>>> Thanks again, >>>>>> - Jeff >>>>>> >>>>>> Uli Sattler wrote: >>>>>>>>>> Notice that the consequent has (x, y), not (x, z) so that z >>>>>>>>>> is >>>>>>>> unbound. I think this >>>>>>>>>> can done by turning ownsCastle(y, z) into a class description >>>>>>>> for y like OwnsCastle(y) with >>>>>>>>>> a someValuesFrom restriction on ownsCastle >>>>>>>>>> >>>>>>>>>> Class: OwnsCastle SubClassOf: ownsCastle some owl:Thing >>>>>>>>>> >>>>>>>>>> Then the rule becomes one which can be converted to OWL: >>>>>>>>>> >>>>>>>>>> hasParent(x, y) ^ OwnsCastle(y) -> hasRichParent(x, y) >>>>>>>>>> >>>>>>>>> >>>>>>>>>> You see what I'm getting at. In general, I'm interested in >>>>>>>> the way that >>>>>>>>>> "Rewriting Rules into SROIQ Axioms" turns >>>>>>>>>> rules with variables into axioms without variables. >>>>>>>>> >>>>>>>>> it's described in the papers mentioned earlier...but I think >>>>>>>> have a question in mind but you don't want to go through the >>>>>>>> algorithm's details? >>>>>>>> >>>>>>>> I am interested in the algorithm details but fear I don't have >>>>>>>> the proper >>>>>>>> context for what I was reading. "Tight Integration of >>>>>>>> Description Logics and Disjunctive Datalog" >>>>>>>> by Rosati talks about integrating DL database with a Datalog >>>>>>>> rules engine >>>>>>>> but you are still expected to write the rules in Datalog. >>>>>>> aaah, so I can understand your difficulties...you can find a >>>>>>> worked-out example that tries to explain the differences between >>>>>>> OWL and rules and their interaction in B. Motik, U. Sattler, and >>>>>>> R. Studer. Query Answering for OWL-DL with Rules. In Proc. of >>>>>>> the >>>>>>> Third International Semantic Web Conference (ISWC 2004), Vol. >>>>>>> 3298 >>>>>>> of Lecture Notes in Computer Science. Springer-Verlag, 2004. >>>> http://www.springerlink.com/content/3ah2ypj3p628ft4m/fulltext.pdf >>>>>>> ...and you can find out more about translating *some* rules >>>>>>> *faithfully* into OWL axioms in E Francis Gasse, Ulrike Sattler, >>>>>>> Volker Haarslev: Rewriting Rules into SROIQ Axioms. Description >>>>>>> Logics 2008 >>>>>>> http://ceur-ws.org/Vol-353/GasseSattlerHaarslev.pdf >>>>>>> Markus Krötzsch, Sebastian Rudolph, Pascal Hitzler. ELP: >>>>>>> Tractable >>>>>>> Rules for OWL 2. ISWC2008, 2008. >>>> http://korrekt.org/papers/KroetzschRudolphHitzler_ELP_TR_2008.pdf >>>>>>> Markus Krötzsch, Sebastian Rudolph, Pascal Hitzler. Description >>>>>>> Logic Rules. ECAI2008, 2008. * >>>>>>> http://korrekt.org/papers/KroetzschRudolphHitzler_SROIQ-Rules_TR_2008.pdf >>>>>>> * >>>>>> >>>>>> >>>>>> >>>>> >>>> >>>> ----------------------------------------------- >>>> 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 >> ----------------------------------------------- >> >> >> >> > ----------------------------------------------- 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 Wednesday, 17 September 2008 15:59:24 UTC