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Re: possible semantic bugs concerning domain and range

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Mon, 23 Sep 2002 16:23:26 -0400 (EDT)
Message-Id: <20020923.162326.90386604.pfps@research.bell-labs.com>
To: phayes@ai.uwf.edu
Cc: www-webont-wg@w3.org

From: pat hayes <phayes@ai.uwf.edu>
Subject: Re: possible semantic bugs concerning domain and range
Date: Mon, 23 Sep 2002 15:04:24 -0500

> 
> ......
> 
> >As far as OWL is concerned,
> >
> >	foo rdfs:range bar .
> >
> >should follow from
> >
> >	foo rdfs:range baz .
> >	baz rdfs:subClassOf bar .
> >
> >This would fit in with the general OWL stance on these sorts of things.
> 
> Come on, I need more than that. What 'general OWL stance' ?? 

The general OWL stance is that if some conclusion is true, such as, in this
case, all the possible object of foo belong to baz, then that should be
inferrable. 

> Does OWL 
> differ so much from DAML+OIL that conjunctive information about 
> property ranges and domains is now considered illegal? 

No, of course not.  There is nothing in OWL that causes

	foo rdfs:range bar .
	foo rdfs:range zyx .

to cause a problem.  All that happens here is that you can infer

	foo rdfs:range _:z .
	_:x owl:intersectionOf [bar xyz] .


> And what does 
> one *gain* by making this change, in any case? 

Precisely inferences like the one above.

> Jeremy's entailment 
> goes through, if properly expressed, with the current semantics for 
> domain and range.

Jeremy's entailment

	1:[[

	eg:prop rdfs:range eg:A .
	eg:A rdfs:subClassOf eg:B .

	entails

	eg:prop rdfs:range eg:B .
	]]

is not a consequence in RDFS.

> The above entailment strikes me as completely wrong, both formally 
> and intuitively. For example, all properties, on this view, have the 
> universe as their range. It basically makes range assertions into 
> un-assertions: their only utility would be enable one to guess (not 
> infer) from the lack of a range assertion that something probably 
> wasn't in the range.

Not at all.  Giving rdfs:range an iff condition is both formally viable and
intuitively defensible. 

> Pat

peter
Received on Monday, 23 September 2002 16:23:36 GMT

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