Re: Comment: Representing Classes As Property Values on the Semantic Web

Natasha Noy wrote:
> Ivan,
> 
> I am not sure I understand: Following your argument, saying
> :LionSubject a owl:Thing
> still technically doesn't preclude it from being an owl:Class, does it?
> 

That is true and that would be a problem with DL. But my point is a bit different: just by 
saying

:LionSubject a :Lion.

you *cannot* infer whether :LionSubject is a owl:Thing or not (unless you know in advance 
that the ontology *is* DL). And the logic of the document is the other way round: we want 
to have an ontology that will, shall we say, safely pass an DL checker, so we have to 
ensure that :LionSubject is also an owl:Thing.

> Natasha
> 
> PS. The document is already a WG Note, so making changes would be  quite 
> difficult logistically, as I understand it.
> 

Well, that might be a show-stopper for this indeed. It is not a major problem, though...

Ivan



> On May 4, 2005, at 6:15 AM, Ivan Herman wrote:
> 
>> My (editorial) comment refers to Approach #2, but is also valid  
>> elsewhere.
>>
>> The text (as well as the code) says:
>>
>> :LionSubject a :Lion.
>>
>> and, sort of, makes the implicit conclusion that this also means
>>
>> :LionSubject a owl:Thing.
>>
>> However, as far as I understand, this is not true per se *unless*  we 
>> know in advance that we are in OWL DL or OWL Light. If we do not  know 
>> that about an ontology, then there is nothing that  precludes 
>> :LionSubject to be also an owl:Class. Because the essence  of the text 
>> is to emphasize using individuals at that point to make  it clearly 
>> DL, I think it would be better to explicitly say:
>>
>> :LionSubject
>>     a owl:Thing;
>>     a :Lion .
>>
>> the same holds for a number of examples later in the text, and the  
>> N3/XML codes.
>>
>> -- 
>>
>> Ivan Herman
>> W3C Communications Team, Head of Offices
>> C/o W3C Benelux Office at CWI, Kruislaan 413
>> 1098SJ Amsterdam, The Netherlands
>> tel: +31-20-5924163; mobile: +31-641044153;
>> URL: http://www.w3.org/People/Ivan/
>>
> 
> 

-- 

Ivan Herman
W3C Communications Team, Head of Offices
C/o W3C Benelux Office at CWI, Kruislaan 413
1098SJ Amsterdam, The Netherlands
tel: +31-20-5924163; mobile: +31-641044153;
URL: http://www.w3.org/People/Ivan/