W3C home > Mailing lists > Public > www-rdf-interest@w3.org > October 2004

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
value?

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
1098SJ Amsterdam, The Netherlands
tel: +31-20-5924163; mobile: +31-641044153;
URL: http://www.w3.org/People/all?pictures=yes#ivan

Received on Saturday, 16 October 2004 06:58:15 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:52:10 GMT