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Re: owl:TopObjectProperty in property chains?

From: Uli Sattler <sattler@cs.man.ac.uk>
Date: Fri, 29 Aug 2008 10:33:31 +0100
Cc: public-owl-dev@w3.org
Message-Id: <890729DC-4A31-4323-8DF8-1BC52004B9A6@cs.man.ac.uk>
To: Jeff Thompson <jeff@thefirst.org>


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
>> *
>
>
>
Received on Friday, 29 August 2008 09:31:59 GMT

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