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Re: Some fuzzy with cardinality restriction vs complex property in OWL

From: Ivan Herman <ivan@w3.org>
Date: Sat, 16 Oct 2004 08:58:35 +0200
Message-ID: <4170C69B.9060202@w3.org>
To: Yuzhong Qu <yzqu@seu.edu.cn>
Cc: www-rdf-interest@w3.org, "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>

Yuzhong Qu wrote:
> The OWL S&AS says:
> To preserve decidability of reasoning in OWL Lite, not all properties 
> can have cardinality restrictions placed on them or be specified as 
> functional or inverse-functional. An individual-valued property is 
> complex if
> 1/ it is specified as being functional or inverse-functional,
> 2/ _there is some cardinality restriction that uses it,_
> 3/ it has an inverse that is complex, or
> 4/ it has a super-property that is complex.
> Complex properties cannot be specified as being transitive.
> It seems OK, but some mistiness arises when diving into the deeps.
> We know that:
> someValuesFrom(owl:Thing) is logically equivalent to minCardinality(1)
> and someValuesFrom(SomeNonEmptyClass) logically implies minCardinality(1)

I am not sure that is true. Isn't it correct that:

- someValuesFrom(owl:Thing) simply means that *if* there are values *then* at least one
myst be from owl:Thing, whereas minCardinality(1) means that there *must* be at least one

and the same for the second statement?

> My questions:
> 1. Suppose there is an existential restriction that uses a 
> property, should the property be considered as a complex property?
> It seems not. But how to explain the implication of the above axioms?
> 2. Is there any meaning with minCardinality(0)? does it make the 
> corresponding property become a complex property?
> e.g.
> restriction( myProperty minCardinality(0)) makes myProperty become a 
> complex property?
> Thanks for your concern!
> Yuzhong Qu 


Ivan Herman
W3C Communications Team, Head of Offices
C/o W3C Benelux Office at CWI, Kruislaan 413
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Received on Saturday, 16 October 2004 06:58:15 GMT

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