Re: [OEP] "Classes as values" first draft


I think you are right that I wasn't clear in what I was trying to say. 
And I hope we can hammer out exactly the right words.

>  My first question when presented with any KR question is "What are 
> you trying to say".
>  The  use case is
>  "We want to be able to say that an image of a Lion is also an image 
> of a Mammal"
>  My italics and boldface of the indefinite articles 'a'.
>  We are NOT saying that this is a picture of the "species Lion" or the 
> "class Lion."

I think the confusion here comes from the ambiguity of the word 
'subject'. I'll try to think of a different example. I used subject 
here (and, again, I think that's the intended interpretation of 
dc:subject) as the topic of the image rather than to describe something 
that is actually shown in the image. Kind of like "Ontologies" can be a 
subject of someone's PhD Thesis. I'll think of using a different 
example for the next draft to avoid the confusion (any suggestions are 
welcome!). In fact, think about books about animals and their subjects. 
Here a book about lions is really a book whose subject is a class Lion 
rather than an individual Lion.

I think that with this interpretation, using class as the value for the 
property can indeed be considered a correct representation (my approach 
1) and matches this interpretation pretty closely (with the benefit of 
being the most intuitive to most people and with the serious drawback 
for many of being outside OWL DL).

I think the option that you propose actually corresponds to a different 
interpretation of subject, where the value for the subject property 
would be the specific lion shown in the picture. In fact, your 

>     LionImage rdf:type restriction(someValuesFrom dc:subject 
> someValuesFrom Lion))  (1)

says exactly that. It will also make any kb that doesn't have that Lion 
individual filling in the property value inconsistent with this 

>  However, I would put forward a version (5) if only to rule it out, 
> that Lion exists in one ontology completely distinct from the image 
> which is being annotated.  The annotation is in RDF and points to the 
> Lion, but it does not add to the ontology - indeed it says nothing 
> about the concept Lion.  Were we to recommend it, it requires that 
> somewhere we capture the semantics that we mean "a Lion" rather than 
> "the class Lion".  That would require annotation properties or other 
> "epicycles".  I think this is much clearer if we stick to variants of 
> (I).

I don't think I understand this option. Perhaps you could clarify it 
some more?

Thanks a lot,


Received on Tuesday, 20 April 2004 20:23:46 UTC