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Re: [OPEN] and/or [PORT] : a practical question

From: Pat Hayes <phayes@ihmc.us>
Date: Tue, 30 Mar 2004 19:55:29 -0800
Message-Id: <p06001f28bc8fc10534fc@[]>
To: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Cc: SWBPD list <public-swbp-wg@w3.org>

>Yes, like Bernard, I have been thinking more about this, and about 
>Ian's insistence in WebOnt that classes-and-instances was almost 
>always raised by people wanting to mismodel their world. (cc Ian, 
>wondering if I have learnt my lessons well!, or misrepresented him)
>The class hierarchy in RDFS/OWL is there to describe hierarchies of 
>classes of resources. Just because you have a hierarchy of subject 
>descriptors doesn't make it a class hierarchy.

No, but if the descriptors is a taxonomy or a generalization 
hierarchy then it is quite natural to identify it with the 
corresponding subClass hierarchy. I agree this is a simplifying 
identification of two things that can be kept conceptually distinct, 
but its often handy to do that, especially if you don't have anything 
very elaborate in mind. .

>It seems to be confusing the human way of thinking of analogy and 
>metaphor (any hierarchy can act as a metaphor for any other 
>hierarchy) with what is a logical and implementation issue about how 
>to say what we want to say about our knowledge of our world in a way 
>that machines can process it.
>Thus if PhDThesis is an owl:Class what are the resources that we 
>intend to belong to it? Probably my PhD Thesis with title "Graph 
>Grammars: an approach to transfer based MT; exemplified by a 
>Turkish-English system" is one such resource, but the copy sitting 
>on my bookshelf is probably not.

Now you are getting into an orthogonal issue, distinguishing between 
types and tokens of texts. Like, Moby Dick the novel (only one of 
them) vs. all the printed copies of Moby Dick (each of which has many 
other attributes than the novel and in fact is a completely different 
kind of thing, eg you can burn one of those but you can't burn a 
novel. But this is orthogonal to the class/instance issue: you can 
have a class of types and a class of tokens (they are disjoint). In 
fact, the class of classes of abstract texts such as novels might be 
a handy metaclass.


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Received on Tuesday, 30 March 2004 22:55:13 EST

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