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RE: Blank Node Equality Question

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Mon, 21 Jul 2003 12:08:17 +0200
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, <jimbobbs@hotmail.com>
Cc: <www-rdf-logic@w3.org>
Message-ID: <BHEGLCKMOHGLGNOKPGHDMENFCBAA.jjc@hpl.hp.com>

> 2/ If two blank nodes are connected to identical nodes via identical
> predicates then can any inference made about the first also be made about
> the second?  In RDF and RDFS this is true.  In many stronger languages,
> including OWL, this is not true.   For example
>
> 	_:a rdf:type ex:Class .
> 	_:b rdf:type ex:Class .
>
> entails in OWL
>
> 	_:a owl:sameAs _:a .
>
> but not
>
> 	_:a owl:sameAs _:b .
>

Completely exchanging _:a for _:b (and vice versa) will always provide a
proof for statements about _:b that are similar to proven statements about
_:a, so that

 _:b owl:sameAs _:b .

follows with a proof identical to that for

  _:a owl:sameAs _:a .

Jeremy
Received on Monday, 21 July 2003 06:08:34 GMT

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