W3C home > Mailing lists > Public > www-webont-wg@w3.org > September 2002

Re: possible semantic bugs concerning domain and range

From: pat hayes <phayes@ai.uwf.edu>
Date: Mon, 23 Sep 2002 22:18:39 -0500
Message-Id: <p05111b4fb9b585c13bc7@[]>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: www-webont-wg@w3.org

Rather than respond point by point, let me try to see if I can 
summarize what seem to be the main clashes of intuition here.

My view of the range of a property is that it is a particular class 
which as far as possible defines the, well, range that the values of 
the property can take. Of course, there is no guarantee that any 
property will as it were 'fill up' its range, so it can make sense to 
apply conjunctive semantics to multiple range assertions; but the 
range is a definite thing associated with the property; it is part of 
the very specification of the property; knowing the range is knowing 
something particular about the property, a key piece of information. 
It allows one, for example, to detect inappropriate uses of the 
property under some circumstances. Ranges can be used to convey 
information relevant to a property, for example by having an 
associated datatype.

Your view, as I understand it, is that a range is simply any class 
which all the values are in. In particular, the idea of there being 
*a* range is silly, on this view: all properties will have multiple 
ranges. What I am calling 'the' range, on this view, is something 
like the smallest range; but supersets of this can also be called 
ranges. I can see that with this view, the proposed semantics  and 
Jeremy's entailment are both quite natural. But what worries me about 
this view is that it seems to discount the most useful aspects of the 
'range' idea.

The first view seems to go naturally with an intensional view of 
classes as real things that can have properties, while the second is 
more natural if one thinks of classes simply as sets in extension. 
Maybe the different directions our intuitions go in reflect a 
basically different world-view about the nature of classes.

However, I would like to return to a more technical debate. You claim 
the several intuitive entailments go through on your semantics but 
not on mine. Seems to me that this isn't correct, so far: the correct 
form of Jeremy's entailment and the intersection example both work on 
both semantics. So just on grounds of interoperability, it seems to 
me that the burden of proof is on you to show why OWL needs to change 
from the RDFS range semantics.


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Received on Monday, 23 September 2002 23:18:32 UTC

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