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Re: Cyclic Classes/Properties

From: Sigfrid Lundberg, Lub NetLab <siglun@gungner.lub.lu.se>
Date: Fri, 11 May 2001 15:59:33 +0200 (MET DST)
To: Enrico Franconi <franconi@cs.man.ac.uk>
cc: www-rdf-logic@w3.org
Message-ID: <Pine.LNX.3.96.1010511155620.153B-100000@gungner>
On Fri, 11 May 2001, Enrico Franconi wrote:

> If you have a propositionally closed representation language, then
> having a not-strict-sub-class-of allows you to have the
> strict-sub-class-of as well. So there is NO trading inferability
> against expressiveness.

You're obviously correct. An obvious follow-up question is: Why doesn't
daml do it this way? Or does it, but I'm not able to see it (because I
might not be able to recognize a "propositionally closed representation
language" when I see it ;).

> This is how you could represent your example:
> 
> Introduce first a freshly new primitive class "non-sub-title".
> Add the following axioms:
> 
> sub-title is-a-not-strict-sub-class-of title.
> title is-a-not-strict-sub-class-of (sub-title or non-sub-title).
> non-sub-title is-a-not-strict-sub-class-of ((not sub-title) and title).
> 
> This implies:
> sub-title is-a-strict-sub-class-of title
> 
> cheers
> -- e.

Have a nice weekend

Sigge
Received on Friday, 11 May 2001 09:47:34 GMT

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