- From: Rinke Hoekstra <hoekstra@uva.nl>
- Date: Wed, 17 Sep 2008 17:09:43 +0200
- To: OWL 2 <public-owl-wg@w3.org>
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 -----------------------------------------------
Received on Wednesday, 17 September 2008 15:10:18 UTC