Comment: Representing Classes As Property Values on the Semantic Web

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
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