# Re: Detecting cycles in OWL

```> 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.
>>
>
> --
> Lingsoft - 30 years of Leading Language Management
>
> www.lingsoft.fi
>
> Speech Applications - Language Management - Translation - Reader's and Writer's Tools - Text Tools - E-books and M-books
>
> Mikael Pesonen
> System Engineer
>
> e-mail: mikael.pesonen@lingsoft.fi
> Tel. +358 2 279 3300
>
> Time zone: GMT+2
>
> Helsinki Office
> Eteläranta 10
> FI-00130 Helsinki
> FINLAND
>
> Turku Office