W3C home > Mailing lists > Public > semantic-web@w3.org > April 2020

Re: Detecting cycles in OWL

From: Paul Tyson <phtyson@sbcglobal.net>
Date: Fri, 24 Apr 2020 10:58:16 -0500
Message-Id: <388BD815-3351-4E34-AA9B-18EF886B1AED@sbcglobal.net>
Cc: Pascal Hitzler <phitzler@googlemail.com>, semantic-web@w3.org
To: Mikael Pesonen <mikael.pesonen@lingsoft.fi>

> On Apr 24, 2020, at 09:12, Mikael Pesonen <mikael.pesonen@lingsoft.fi> wrote:
> 
> 
> Thanks Pascal, saves lot's of time if this is not possible by normal OWL DL means. That PDF looks like worth atleast trying to understand.
> 
> Followup question to forum: how does one continue usually when reasoning capabilities hit the wall? SWRL and SPARQL queries are the next steps?
> 
In my experience, “reasoning” is not as useful for practical business problems as directly implementing relevant business rules. A path that worked well for me was:

RIF -> SPARQL -> whatever

Starting with RIF provided greater visibility for business rules and all the other benefits of an open exchange format: documentation, reuse, repurposing, ....

Regards,
—Paul
> 
> 
>> On 24/04/2020 17.01, Pascal Hitzler wrote:
>> You probably find more about these matter than you care about here: http://people.cs.ksu.edu/~hitzler/resources/publications/OWL-Rules-2011.pdf
>> 
>> But let me break down your example.
>> 
>> you want to say something like the following:
>> 
>> A(x) AND p1(x,y) AND C(y) AND p2(y,z) AND B(z) AND p4(w,z) AND D(w) AND p3(x,w) --> E(x)
>> 
>> And essentially you want to know whether there is anything in the class E.
>> 
>> With the rolification technique in the above referenced paper, yo would come up with the following to express the axiom:
>> 
>> A equiv exists R_A.Self
>> B equiv exist R_B.Self
>> C equiv exists R_C.Self
>> D equiv exists R_D.Self
>> R_A o p1 o R_C o p2 o R_B o p4- o R_D o p3- subPropertyOf R
>> exists R.Self subClassOf E
>> 
>> Now, these six axioms *syntactically* translated into first-order predicate logic do the trick.
>> 
>> HOWEVER, you would use Self with a non-simple role, which is not allowed under OWL DL.
>> 
>> So the short answer is: it doesn't look like it's possible.
>> 
>> The above paper discusses a construct called nominal schemas, which is (very complex) syntactic sugar on top of OWL, an which allows you to express the rule above, provided that the variable x can bind only to individuals actually occurring in the knowledge base.
>> 
>> Best Regards,
>> 
>> Pascal.
>> 
> 
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Received on Friday, 24 April 2020 15:58:34 UTC

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