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Re: ISSUE-119: What can be done against the Russell paradox?

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Sun, 27 Apr 2008 09:44:51 -0400 (EDT)
Message-Id: <20080427.094451.105652406.pfps@research.bell-labs.com>
To: schneid@fzi.de
Cc: public-owl-wg@w3.org

From: "Michael Schneider" <schneid@fzi.de>
Subject: RE: ISSUE-119: What can be done against the Russell paradox?
Date: Sun, 27 Apr 2008 13:41:19 +0200

[...]

> >But, again, what did you expect in OWL Full?   OWL 1 Full was dancing
> >right up against the cliff.   Adding useful expressive power to OWL
> >requires delicate work so that OWL Full doesn't fall into the abyss.
> >As an alternative, I suppose that the WG could just go the N3 way with
> >OWL Full.
> 
> I am not yet convinced that an RDFS-based language needs to be close to the 
> abyss when it tries to compete with OWL DL w.r.t. semantic expressivity. Maybe 
> the problem has rather to do with the way how the semantic expressivity is 
> compared for these two languages.
> 
> What I would like to know is the following: What was the motivation to compare 
> OWL DL (a description logic) with OWL Full (an RDFS-based logic) on the basis 
> of common entailments? 

This comes from the RDF semantics, which concentrates on entailment.
Because of this, it made the most sense to compare using entailments.
Note that description logics generally talk about particular inference
services, like subsumption and classification, not general entailment.

> I.e. why is there a criterion (Theorem 2) of the style: 
> "If the RDF graph O1 DL-entails the RDF graph O2, then O1 is also required to 
> Full-entail O2."? I would expect that such a criterion only makes sense, if 
> the semantic meaning of the syntactic expression O1 is the same both under OWL 
> DL and OWL Full semantics, and ditto for O2.

The whole idea of Theorem 2 was to try to determine how close the
semantic meanings were between OWL 1 DL and OWL 1 Full.

> Btw: What do you mean by "the N3 way"?

No syntax for OWL Full, no semantics for OWL Full.

> Michael

peter
Received on Sunday, 27 April 2008 13:47:14 GMT

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