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[protege-owl] existentials and the OWLThing built-in [Re: Re: SWRL doubt: using rules to add new individuals? (Samson Tu)]

Martin O'Connor martin.oconnor at
Thu Aug 30 16:55:00 PDT 2007

While the owl:someValuesFrom restriction can in principle be used to  
support existentials in SWRL rules, no OWL reasoners that support SWRL  
currently implement this functionality. The two significant systems  
that I am aware of (Pellet and KAON2) implement so called DL-safe SWRL  
rules, which effectively ignore OWL axioms. The SWRLTab Jess bridge  
also does not support most OWL axioms.


Quoting Samson Tu <swt at>:

> Nacho Mayorga wrote:
> ...
>> - first of all, I'd need the new individual to belong to a specific
>> class, not just OWLThing. Will it be possible either forcing the class
>> or changing it later (though still in the same rule)?
> Assert the class of the newly-created individual on the consequent side
> of the rule. You need all variables instantiated on the antecedent of
> the rule.
> I'll let others answer the other questions, except to say that SWRLtab
> doesn't support the use of existential restriction, and all built-ins
> are out of the reach of classifiers. HOwever, once you import the new
> individuals (from SWRLtab) to OWL, they are indistinguishable from others.
>> - I'm not sure whether using the built-in in the antecedent would be
>> what I needed, but I guess that, having all the variables instantiated,
>> it should be the same
>> - and, finally, the explanation in the wiki reads:
>>     However, while not convenient, existential created in this way are
>>     theoretically safe. In contrast, existentials created using this
>>     built-in will be beyond the immediate reach of OWL classifiers. They
>>     should probably not be stored permanently in an OWL ontology.
>> with the first sentence referring to the existential restriction
>> owl:someValuesFrom for adding new individuals. Could you, please,
>> explain why
>> a) the existentials created by means of owl:someValuesFrom are not
>> convenient?
>> and why the individuals created by using this built-in (createOWLThing)
>> would be
>>   b) out of the immediate reach of classifiers and
>>   c) should probably not be stored permanently in the ontology?
>> Thanks a lot once again,
>>                                                  Nacho
>> --
>> Nacho Mayorga
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> --
> Samson Tu                    email: swt at
> Senior Research Scientist    web:
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