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[protege-owl] Different levels of relations

Paulo Urbano pub at
Mon Nov 8 10:42:25 PST 2010

Thanks again

Great help Thomas


2010/11/8 Thomas Russ <tar at>

> On Nov 7, 2010, at 5:09 AM, Paulo Urbano wrote:
>  Regarding Thomas solution 4:
>> 4.  You could dispense with the individuals entirely and work just with
>> the descriptions and the axioms describing the restrictions.  So, for
>> example you could say
>>  John type (some likes Music)
>>  Frida type (some likes Rock)
>> etc.  You could then use things like DL query to find individuals that
>> satisfy the restrictions that you want.  This can be a bit cumbersome in
>> that getting access to the details of the restrictions isn't as easy as
>> dealing directly with individuals and property values, but it should be
>> something you could reasonably encapsulate.
>> Wouldn't the ontology be inconsistent as the existential restriction would
>> imply that John and Frida must have a value (individual) for class Music and
>> Rock respectively?
> Why do you think this would make the ontology inconsistent?
> Existential quantifiers do not require an actual individual filler because
> of open world semantics.
> Now, one could debate whether there really is an individual of Music or
> Rock that the individual likes.  But perhaps the interpretation that you
> want is that the individual likes some songs that are Rock_Songs.  This is,
> of course, a relatively weak statement, since the SOME qualifier only
> requires one.  So there is a bit of a mismatch in the strict logical
> interpretation and the more common sense view of what it means to like Rock
> or Jazz.  But within the limitations of the OWL-DL language, you often have
> to make some accommodations to the expressive power and the need for crisp
> logical definitions of what are, in reality, more fuzzy notions.
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