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RE: SEM: comprehensive entailments without dark triples

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Tue, 23 Apr 2002 03:20:19 -0400
To: jjc@hplb.hpl.hp.com
Cc: www-webont-wg@w3.org
Message-Id: <20020423032019X.pfps@research.bell-labs.com>
From: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
Subject: RE: SEM: comprehensive entailments without dark triples
Date: Mon, 22 Apr 2002 17:28:12 +0100

> > 
> > The problem with these comprehension principles is that they do not
> > generate non-tree structures.  Therefore classes that are not in the form
> > of trees (yes, this is rather vague, but my previous message gives one
> > example) will not be consequences.
> > 
> 
> I agree, that was an objective.
> 
> Jeremy

Huh?

Do you mean that classes that are not in the form of trees will not be
consequences?  This leads to what is to me a very strange logical system in
which the comprehension principle only works for some kinds of
restrictions.

Consider the following KB:

KB1:

	John rdf:type Person .
	John rdf:type :_1 .
	:_1 daml:onProperty child .
	:_1 daml:cardinality "0" .

As John has no children it seems to me that it should be a theorem of the
logical system that John belongs to any value restriction on child.

However, this is not the case.
Consider the following KBs:

KB2:

	:_2 daml:onProperty child .
	:_2 daml:toClass Person .

KB3:

	:_3 daml:onProperty child .
	:_3 daml:toClass :_3.

KB1 entails KB2, but does not entail KB3.

peter
Received on Tuesday, 23 April 2002 03:21:32 GMT

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